⚡ Quick Answer
CompTIA’s official Security+ SY0-701 acronym list has 336 entries covering 330 acronyms. MAC has three meanings, and PAM, RA, RBAC and SAN each have two. All 336 entries are in the table below.
This is the acronym list from the official CompTIA Security+ SY0-701 exam objectives (document version 7.0). CompTIA describes it as the acronyms that appear on the SY0-701 exam. The “Stands for” column gives each expansion exactly as CompTIA writes it. Where CompTIA’s wording differs from the name most sources use, the “What it is” column often notes the usual name. Exam details are on CompTIA’s Security+ certification page.
This list is for SY0-701. SY0-801 (V8) launches on or around November 17, 2026 and has its own acronym list; SY0-701 remains available until June 11, 2027 (English).
SY0-701 acronyms, A to Z
| Acronym | Stands for | What it is | Guide |
|---|---|---|---|
| 2FA | Two-factor Authentication | Login that requires two different kinds of proof, such as a password plus a code from your phone. | Multi-factor authentication (MFA) |
| 3DES | Triple Data Encryption Standard | Older block cipher that runs DES three times per block; NIST disallowed it for encryption after 2023. | Symmetric vs asymmetric encryption |
| AAA | Authentication, Authorization, and Accounting | Framework for proving who a user is, controlling what they can do, and logging what they did. | RADIUS |
| ACL | Access Control List | Ordered list of rules that permits or denies traffic or access based on criteria like IP address or user. | Firewall basics |
| AES | Advanced Encryption Standard | Symmetric block cipher standardized by NIST; the current standard for encrypting data, with 128-, 192- or 256-bit keys. | Symmetric vs asymmetric encryption |
| AES-256 | Advanced Encryption Standards 256-bit | AES used with a 256-bit key, its strongest key size; officially Advanced Encryption Standard. | Symmetric vs asymmetric encryption |
| AH | Authentication Header | IPsec protocol that authenticates packets and protects their integrity but does not encrypt them. | VPNs |
| AI | Artificial Intelligence | Computer systems that perform tasks normally requiring human judgment, such as recognizing patterns or generating text. | A+ AI concepts (Core 2 objective 4.10) |
| AIS | Automated Indicator Sharing | U.S. CISA program for sharing machine-readable cyber threat indicators between government and private organizations. | |
| ALE | Annualized Loss Expectancy | Expected yearly cost of a risk: single loss expectancy multiplied by annualized rate of occurrence. | Risk management |
| AP | Access Point | Device that connects wireless clients to a wired network. | Wireless networking |
| API | Application Programming Interface | Defined interface that lets one program request data or actions from another. | |
| APT | Advanced Persistent Threat | Well-resourced attacker, often state-sponsored, that gains access and stays hidden in a network for a long time. | Threat intelligence |
| ARO | Annualized Rate of Occurrence | Estimated number of times a specific loss is expected to occur in a year. | Risk management |
| ARP | Address Resolution Protocol | Protocol that maps IPv4 addresses to MAC addresses on a local network. | Network attacks |
| ASLR | Address Space Layout Randomization | Memory protection that randomizes where code and data load, making memory-corruption exploits harder. | |
| ATT&CK | Adversarial Tactics, Techniques, and Common Knowledge | MITRE knowledge base that catalogs real-world attacker tactics and techniques. | Threat intelligence |
| AUP | Acceptable Use Policy | Policy listing what users may and may not do with an organization's systems and data. | |
| AV | Antivirus | Software that detects and removes malicious software, traditionally by matching known signatures. | Endpoint detection and response (EDR) |
| BASH | Bourne Again Shell | Command-line shell and scripting language used on Linux and macOS. | |
| BCP | Business Continuity Planning | Planning to keep critical business functions running during and after a disruption. | Business continuity and disaster recovery |
| BGP | Border Gateway Protocol | Routing protocol that exchanges routes between autonomous systems across the internet. | Routing protocols |
| BIA | Business Impact Analysis | Analysis of how disruptions would affect business functions; it sets recovery priorities and targets. | Business continuity and disaster recovery |
| BIOS | Basic Input/Output System | Legacy firmware that initializes hardware and starts the operating system at boot. | BIOS vs UEFI |
| BPA | Business Partners Agreement | Agreement defining the responsibilities, profit sharing and obligations between business partners. | |
| BPDU | Bridge Protocol Data Unit | Message switches exchange in Spanning Tree Protocol to prevent switching loops. | Spanning Tree Protocol (STP) |
| BYOD | Bring Your Own Device | Policy that lets employees use personally owned devices for work. | Mobile device management (MDM) |
| CA | Certificate Authority | Trusted entity that issues and signs digital certificates. | PKI and digital certificates |
| CAPTCHA | Completely Automated Public Turing Test to Tell Computers and Humans Apart | Challenge test that tries to tell human users apart from automated bots. | |
| CAR | Corrective Action Report | Document that records a problem, its cause, and the corrective actions taken. | |
| CASB | Cloud Access Security Broker | Security control point between users and cloud services that enforces policy and visibility. | Cloud security |
| CBC | Cipher Block Chaining | Block cipher mode where each plaintext block is XORed with the previous ciphertext block before encryption. | |
| CCMP | Counter Mode/CBC-MAC Protocol | AES-based encryption protocol used by WPA2 for confidentiality and integrity. | Wireless security protocols |
| CCTV | Closed-circuit Television | Video camera surveillance system viewed or recorded on a private network. | Physical security controls |
| CERT | Computer Emergency Response Team | Team that coordinates responses to computer security incidents and shares related advisories. | |
| CFB | Cipher Feedback | Block cipher mode that turns a block cipher into a self-synchronizing stream cipher. | |
| CHAP | Challenge Handshake Authentication Protocol | Authentication protocol that uses a challenge-response with a hashed shared secret instead of sending the password. | |
| CIA | Confidentiality, Integrity, Availability | The three core security goals: keep data secret, keep it accurate, and keep it accessible. | |
| CIO | Chief Information Officer | Executive responsible for an organization's information technology strategy. | |
| CIRT | Computer Incident Response Team | Team responsible for handling computer security incidents. | |
| CMS | Content Management System | Software for creating and managing website content, such as WordPress. | |
| COBO | Corporate-owned, Business-only | Mobile deployment model where the company owns the device and it is used only for work. | Mobile device management (MDM) |
| COOP | Continuity of Operation Planning | Planning to keep essential functions operating during an emergency; usually called Continuity of Operations planning. | |
| COPE | Corporate Owned, Personally Enabled | Mobile deployment model where the company owns the device but allows some personal use. | Mobile device management (MDM) |
| CP | Contingency Planning | Planning alternate procedures for operating when normal systems or processes fail. | |
| CRC | Cyclical Redundancy Check | Error-detecting check value used to catch accidental data corruption; usually called cyclic redundancy check. | |
| CRL | Certificate Revocation List | List published by a certificate authority of certificates it has revoked before expiration. | PKI and digital certificates |
| CSO | Chief Security Officer | Executive responsible for an organization's overall security. | |
| CSP | Cloud Service Provider | Company that delivers cloud computing services such as IaaS, PaaS or SaaS. | |
| CSR | Certificate Signing Request | Request sent to a certificate authority containing a public key and identity details for a certificate. | |
| CSRF | Cross-site Request Forgery | Attack that tricks a logged-in user's browser into sending unwanted requests to a trusted site. | Application security |
| CSU | Channel Service Unit | Device that connects customer equipment to a digital leased line such as a T1. | |
| CTM | Counter Mode | Block cipher mode that encrypts a counter to produce a keystream; usually abbreviated CTR. | |
| CTO | Chief Technology Officer | Executive responsible for an organization's technology and technical direction. | |
| CVE | Common Vulnerability Enumeration | Public catalog of known vulnerabilities with unique IDs; MITRE names it Common Vulnerabilities and Exposures. | Vulnerability scanning |
| CVSS | Common Vulnerability Scoring System | Standard 0–10 scoring system for rating the severity of vulnerabilities. | Vulnerability scanning |
| CYOD | Choose Your Own Device | Mobile deployment model where employees pick a work device from an approved list. | Mobile device management (MDM) |
| DAC | Discretionary Access Control | Access control model where the resource owner decides who gets access. | Identity and access management |
| DBA | Database Administrator | Person responsible for installing, maintaining and securing databases. | |
| DDoS | Distributed Denial of Service | Denial-of-service attack launched from many systems at once, often a botnet. | Network attacks |
| DEP | Data Execution Prevention | Memory protection that marks data regions non-executable so injected code can't run there. | |
| DES | Digital Encryption Standard | Old 56-bit symmetric cipher, officially the Data Encryption Standard; now insecure. | Symmetric vs asymmetric encryption |
| DHCP | Dynamic Host Configuration Protocol | Protocol that automatically assigns IP addresses and network settings to devices. | DHCP |
| DHE | Diffie-Hellman Ephemeral | Diffie-Hellman key exchange with temporary keys for each session, providing forward secrecy. | Symmetric vs asymmetric encryption |
| DKIM | DomainKeys Identified Mail | Email authentication that adds a digital signature so receivers can verify the sending domain. | Email security (SPF, DKIM, DMARC) |
| DLL | Dynamic Link Library | Windows library file containing code that multiple programs can load and share. | |
| DLP | Data Loss Prevention | Tools and policies that detect and block sensitive data from leaving the organization. | Data loss prevention (DLP) |
| DMARC | Domain Message Authentication Reporting and Conformance | DNS-published email policy for mail failing aligned SPF and DKIM, with reporting; officially Domain-based Message Authentication, Reporting, and Conformance. | Email security (SPF, DKIM, DMARC) |
| DNAT | Destination Network Address Translation | NAT that changes a packet's destination address, often used to forward traffic to internal servers. | |
| DNS | Domain Name System | System that translates domain names into IP addresses. | DNS |
| DNSSEC | Domain Name System Security Extensions | Extensions that digitally sign DNS records so resolvers can verify they are authentic. | DNS security (DNSSEC, DoH, DoT) |
| DoS | Denial of Service | Attack that makes a system or service unavailable to legitimate users. | Network attacks |
| DPO | Data Privacy Officer | Role responsible for an organization's data privacy compliance; under GDPR it's the Data Protection Officer. | Security frameworks |
| DRP | Disaster Recovery Plan | Documented procedures for restoring IT systems and data after a disaster. | Business continuity and disaster recovery |
| DSA | Digital Signature Algorithm | Public-key algorithm for creating and verifying digital signatures. | |
| DSL | Digital Subscriber Line | Internet access delivered over telephone copper lines. | WAN technologies |
| EAP | Extensible Authentication Protocol | Authentication framework that supports many methods, used with 802.1X and wireless networks. | RADIUS |
| ECB | Electronic Code Book | Block cipher mode that encrypts each block independently, leaking patterns; considered insecure. | |
| ECC | Elliptic Curve Cryptography | Public-key cryptography based on elliptic curves, giving strong security with shorter keys. | Symmetric vs asymmetric encryption |
| ECDHE | Elliptic Curve Diffie-Hellman Ephemeral | Elliptic curve key exchange using temporary keys per session, providing forward secrecy. | Symmetric vs asymmetric encryption |
| ECDSA | Elliptic Curve Digital Signature Algorithm | Digital signature algorithm based on elliptic curve cryptography. | Encryption types |
| EDR | Endpoint Detection and Response | Endpoint security that records activity, detects threats and supports investigation and response. | Endpoint detection and response (EDR) |
| EFS | Encrypted File System | Windows feature that encrypts individual files and folders on NTFS volumes; Microsoft calls it Encrypting File System. | |
| ERP | Enterprise Resource Planning | Integrated software that manages core business processes such as finance and supply chain. | |
| ESN | Electronic Serial Number | Unique serial number that identifies a mobile device. | |
| ESP | Encapsulated Security Payload | IPsec protocol that encrypts packet payloads; the RFC calls it Encapsulating Security Payload. | VPNs |
| EULA | End User License Agreement | License agreement between the software publisher and the user. | |
| FACL | File System Access Control List | Access control list on files and directories that grants permissions beyond basic owner/group/other. | |
| FDE | Full Disk Encryption | Encryption of an entire storage drive so data is unreadable without the key. | |
| FIM | File Integrity Management | Monitoring that detects unauthorized changes to files; commonly called file integrity monitoring. | |
| FPGA | Field Programmable Gate Array | Integrated circuit that can be reprogrammed after manufacturing. | |
| FRR | False Rejection Rate | How often a biometric system wrongly rejects an authorized user. | Physical security controls |
| FTP | File Transfer Protocol | Protocol for transferring files that sends data, including credentials, unencrypted. | Port numbers reference |
| FTPS | Secured File Transfer Protocol | FTP protected with TLS; also called FTP Secure or FTP over SSL/TLS. | Port numbers reference |
| GCM | Galois Counter Mode | Block cipher mode that provides both encryption and integrity (authenticated encryption). | |
| GDPR | General Data Protection Regulation | European Union law governing the protection and privacy of personal data. | Security frameworks |
| GPG | Gnu Privacy Guard | Free, open-source implementation of the OpenPGP standard; officially GNU Privacy Guard. | |
| GPO | Group Policy Object | Set of Windows settings applied to users and computers through Active Directory. | Group Policy (GPOs) |
| GPS | Global Positioning System | Satellite navigation system that provides device location. | |
| GPU | Graphics Processing Unit | Processor specialized for parallel calculations such as graphics. | PC hardware components |
| GRE | Generic Routing Encapsulation | Tunneling protocol that encapsulates packets inside IP; provides no encryption by itself. | |
| HA | High Availability | Designing systems to keep running with minimal downtime, typically through redundancy. | Load balancing |
| HDD | Hard Disk Drive | Storage device that records data on spinning magnetic platters. | Storage types (HDD, SSD, NVMe) |
| HIDS | Host-based Intrusion Detection System | Software on a host that monitors that system for signs of intrusion and raises alerts. | IDS vs IPS |
| HIPS | Host-based Intrusion Prevention System | Software on a host that detects and blocks suspicious activity on that system. | IDS vs IPS |
| HMAC | Hashed Message Authentication Code | Code that uses a hash function and secret key to verify integrity and authenticity; officially keyed-hash message authentication code. | Cryptography |
| HOTP | HMAC-based One-time Password | One-time password generated from a shared secret and a counter. | Multi-factor authentication (MFA) |
| HSM | Hardware Security Module | Tamper-resistant hardware device that generates, stores and uses cryptographic keys. | |
| HTML | Hypertext Markup Language | Markup language used to structure web pages. | |
| HTTP | Hypertext Transfer Protocol | Protocol for transferring web content, unencrypted. | Port numbers reference |
| HTTPS | Hypertext Transfer Protocol Secure | HTTP encrypted with TLS. | Port numbers reference |
| HVAC | Heating, Ventilation Air Conditioning | Building systems for heating, ventilation and air conditioning; often networked and a security concern. | |
| IaaS | Infrastructure as a Service | Cloud model where the provider supplies virtualized compute, storage and networking you manage. | Cloud computing concepts |
| IaC | Infrastructure as Code | Defining and deploying infrastructure through code files rather than manual configuration. | Cloud security |
| IAM | Identity and Access Management | Processes and tools for managing digital identities and controlling their access. | Identity and access management |
| ICMP | Internet Control Message Protocol | Network-layer protocol for error messages and diagnostics, such as ping. | Network troubleshooting commands |
| ICS | Industrial Control Systems | Systems that monitor and control industrial processes such as manufacturing and utilities. | |
| IDEA | International Data Encryption Algorithm | Symmetric block cipher with a 128-bit key, used in early versions of PGP. | |
| IDF | Intermediate Distribution Frame | Wiring closet that connects end-user cabling on a floor to the main distribution frame. | |
| IdP | Identity Provider | Service that authenticates users and issues identity assertions to other applications. | |
| IDS | Intrusion Detection System | System that monitors network or host activity and alerts on suspected attacks without blocking them. | IDS vs IPS |
| IEEE | Institute of Electrical and Electronics Engineers | Professional organization that publishes technology standards, such as 802.11 Wi-Fi and 802.1X. | |
| IKE | Internet Key Exchange | Protocol that negotiates keys and security associations for IPsec. | VPNs |
| IM | Instant Messaging | Real-time text messaging between users. | |
| IMAP | Internet Message Access Protocol | Email protocol for reading messages that stay stored on the mail server. | Port numbers reference |
| IoC | Indicators of Compromise | Evidence that a system may have been breached, such as malicious IP addresses or file hashes. | Threat intelligence |
| IoT | Internet of Things | Network-connected everyday devices such as sensors, cameras and smart appliances. | |
| IP | Internet Protocol | Network-layer protocol that addresses and routes packets between networks. | The TCP/IP model |
| IPS | Intrusion Prevention System | Inline system that detects and blocks suspected attacks in real time. | IDS vs IPS |
| IPSec | Internet Protocol Security | Protocol suite that authenticates and encrypts IP packets, often used for VPNs. | VPNs |
| IR | Incident Response | The process of preparing for, detecting, containing and recovering from security incidents. | Incident response |
| IRC | Internet Relay Chat | Older text-based chat protocol, historically used for botnet command and control. | |
| IRP | Incident Response Plan | Documented plan describing how an organization handles security incidents. | |
| ISO | International Standards Organization | Standards body (officially the International Organization for Standardization) that publishes standards like ISO/IEC 27001. | Security frameworks |
| ISP | Internet Service Provider | Company that provides internet access. | |
| ISSO | Information Systems Security Officer | Person responsible for maintaining the security of a specific information system. | |
| IV | Initialization Vector | Random or unique value combined with a key so identical plaintexts encrypt differently. | Wireless security protocols |
| KDC | Key Distribution Center | Kerberos server that authenticates users and issues tickets. | Kerberos |
| KEK | Key Encryption Key | Key used only to encrypt other keys. | |
| L2TP | Layer 2 Tunneling Protocol | Tunneling protocol commonly paired with IPsec for encryption in VPNs. | VPNs |
| LAN | Local Area Network | Network covering a small area such as a home, office or building. | |
| LDAP | Lightweight Directory Access Protocol | Protocol for querying and managing directory services such as Active Directory. | LDAP |
| LEAP | Lightweight Extensible Authentication Protocol | Cisco's proprietary EAP method that uses MS-CHAP; it is vulnerable to dictionary attacks. | Wireless security protocols |
| MaaS | Monitoring as a Service | Cloud-delivered service that monitors systems, networks or applications. | |
| MAC | Mandatory Access Control | Access control model where the system enforces access using security labels and clearances. | Identity and access management |
| MAC | Media Access Control | Data link sublayer that controls access to the network medium; MAC addresses are named after it. | MAC addresses |
| MAC | Message Authentication Code | Short value generated with a secret key that verifies a message's integrity and authenticity. | |
| MAN | Metropolitan Area Network | Network spanning a city or metropolitan area. | |
| MBR | Master Boot Record | First sector of a disk holding the partition table and boot loader on legacy BIOS systems. | BIOS vs UEFI |
| MD5 | Message Digest 5 | 128-bit hash function that is broken for collision resistance; unsafe for security. | Cryptography |
| MDF | Main Distribution Frame | Central wiring point where building cabling and external connections terminate. | |
| MDM | Mobile Device Management | Centralized management and security policy enforcement for mobile devices. | Mobile device management (MDM) |
| MFA | Multifactor Authentication | Authentication that requires two or more different factor types. | Multi-factor authentication (MFA) |
| MFD | Multifunction Device | Device that combines functions such as printing, scanning, copying and faxing. | |
| MFP | Multifunction Printer | Printer that also scans, copies and faxes. | |
| ML | Machine Learning | Branch of AI where systems learn patterns from data rather than following explicit rules. | |
| MMS | Multimedia Message Service | Mobile messaging standard for sending pictures, video and audio; usually Multimedia Messaging Service. | |
| MOA | Memorandum of Agreement | Document outlining cooperative terms between parties; typically more specific than an MOU. | |
| MOU | Memorandum of Understanding | Document expressing shared intent between parties, usually not legally binding. | |
| MPLS | Multi-protocol Label Switching | Carrier technology that forwards traffic using short labels instead of IP lookups. | WAN technologies |
| MSA | Master Service Agreement | Contract setting the general terms for future work between parties. | |
| MSCHAP | Microsoft Challenge Handshake Authentication Protocol | Microsoft's version of CHAP; MS-CHAPv2 is used in PEAP and has known weaknesses. | |
| MSP | Managed Service Provider | Company that remotely manages a customer's IT infrastructure. | |
| MSSP | Managed Security Service Provider | Company that provides outsourced security monitoring and management. | Security operations centers (SOC) |
| MTBF | Mean Time Between Failures | Average time a repairable system runs between failures. | Business continuity and disaster recovery |
| MTTF | Mean Time to Failure | Average time until a non-repairable component fails. | |
| MTTR | Mean Time to Recover | Average time it takes to restore a failed system; also expanded as mean time to repair. | Business continuity and disaster recovery |
| MTU | Maximum Transmission Unit | Largest packet size a network link can carry without fragmentation. | |
| MX | Mail Exchange | DNS record that specifies which mail servers accept email for a domain. | DNS record types |
| NAC | Network Access Control | Controls that check users and devices before allowing them onto the network. | RADIUS |
| NAT | Network Address Translation | Translates IP addresses between networks, commonly private to public. | NAT |
| NDA | Non-disclosure Agreement | Contract that requires parties to keep shared information confidential. | |
| NFC | Near Field Communication | Very short-range wireless communication used for contactless payments and badges. | |
| NGFW | Next-generation Firewall | Firewall that adds application awareness and intrusion prevention to stateful inspection. | Firewall types |
| NIDS | Network-based Intrusion Detection System | Sensor that monitors network traffic for signs of attack and raises alerts. | IDS vs IPS |
| NIPS | Network-based Intrusion Prevention System | Inline network device that detects and blocks attacks in traffic. | IDS vs IPS |
| NIST | National Institute of Standards & Technology | U.S. federal agency that publishes cybersecurity standards and guidance such as the NIST CSF. | Security frameworks |
| NTFS | New Technology File System | Windows file system that supports permissions, encryption and journaling. | |
| NTLM | New Technology LAN Manager | Legacy Microsoft challenge-response authentication protocol, largely replaced by Kerberos. | Authentication protocols (Kerberos, NTLM, RADIUS, TACACS+) |
| NTP | Network Time Protocol | Protocol that synchronizes system clocks over a network. | NTP |
| OAUTH | Open Authorization | Authorization framework that lets an app access resources on a user's behalf without their password. | Identity and access management |
| OCSP | Online Certificate Status Protocol | Protocol for checking a single certificate's revocation status in real time. | PKI and digital certificates |
| OID | Object Identifier | Globally unique dotted-number identifier, used in SNMP MIBs and X.509 certificates. | SNMP |
| OS | Operating System | Software that manages hardware and runs applications, such as Windows or Linux. | |
| OSINT | Open-source Intelligence | Intelligence gathered from publicly available sources. | Threat intelligence |
| OSPF | Open Shortest Path First | Link-state routing protocol used within an organization's network. | Routing protocols |
| OT | Operational Technology | Hardware and software that monitor and control physical equipment and processes. | |
| OTA | Over the Air | Delivering software or firmware updates wirelessly to devices. | |
| OVAL | Open Vulnerability Assessment Language | Language for describing system configuration checks and vulnerabilities, part of SCAP. | |
| OWASP | Open Worldwide Application Security Project | Nonprofit foundation that publishes web application security guidance, including the OWASP Top 10. | Application security |
| P12 | PKCS #12 | File format that bundles a private key and its certificates, usually password-protected (.p12 or .pfx). | |
| P2P | Peer to Peer | Network model where devices share resources directly without a central server. | |
| PaaS | Platform as a Service | Cloud model where the provider manages the platform and you deploy your own applications. | Cloud computing concepts |
| PAC | Proxy Auto Configuration | File that tells browsers which proxy to use for a given URL. | Proxy servers |
| PAM | Privileged Access Management | Tools and processes that control and monitor administrative accounts and elevated access. | Identity and access management |
| PAM | Pluggable Authentication Modules | Linux/Unix framework that lets applications plug in different authentication methods. | |
| PAP | Password Authentication Protocol | Authentication protocol that sends passwords in cleartext; considered insecure. | |
| PAT | Port Address Translation | NAT where many internal hosts share one public IP, distinguished by port numbers. | NAT |
| PBKDF2 | Password-based Key Derivation Function 2 | Key derivation function that hashes a password many times with a salt to slow brute-force attacks. | |
| PBX | Private Branch Exchange | Private telephone switching system inside an organization. | |
| PCAP | Packet Capture | Captured network traffic, and the common file format used to save it. | |
| PCI DSS | Payment Card Industry Data Security Standard | Security standard required for organizations that store, process or transmit payment card data. | Security frameworks |
| PDU | Power Distribution Unit | Device that distributes electrical power to equipment in a rack. | |
| PEAP | Protected Extensible Authentication Protocol | EAP method that protects the authentication exchange inside a TLS tunnel. | RADIUS |
| PED | Personal Electronic Device | Portable personal device such as a phone, tablet or laptop. | |
| PEM | Privacy Enhanced Mail | Base64 text format for certificates and keys with BEGIN/END lines, named after the old Privacy Enhanced Mail standard. | |
| PFS | Perfect Forward Secrecy | Key exchange property where compromising a long-term key doesn't expose past session keys. | Symmetric vs asymmetric encryption |
| PGP | Pretty Good Privacy | Encryption program and standard for signing and encrypting email and files. | |
| PHI | Personal Health Information | Health-related personal information protected by laws such as HIPAA (HIPAA calls it protected health information). | Data loss prevention (DLP) |
| PII | Personally Identifiable Information | Information that can identify a specific person, such as a name plus Social Security number. | |
| PIV | Personal Identity Verification | U.S. federal smart card standard for employee identity and authentication. | Multi-factor authentication (MFA) |
| PKCS | Public Key Cryptography Standards | Family of standards defining public-key cryptography formats, such as PKCS #12. | |
| PKI | Public Key Infrastructure | Framework of certificate authorities, certificates and policies for managing public keys. | PKI and digital certificates |
| POP | Post Office Protocol | Email protocol that downloads messages from the server to the client, optionally deleting them from the server. | Port numbers reference |
| POTS | Plain Old Telephone Service | Traditional analog landline telephone service. | |
| PPP | Point-to-Point Protocol | Protocol for direct links between two nodes, such as dial-up connections. | |
| PPTP | Point-to-Point Tunneling Protocol | Legacy VPN protocol with known security weaknesses. | VPNs |
| PSK | Pre-shared Key | Shared secret configured on both ends, such as a Wi-Fi password. | Wireless security protocols |
| PTZ | Pan-tilt-zoom | Security camera that can be remotely panned, tilted and zoomed. | |
| PUP | Potentially Unwanted Program | Unwanted software, often bundled with downloads, such as adware or toolbars. | |
| RA | Recovery Agent | Account authorized to recover encrypted data or keys when the original key is unavailable. | |
| RA | Registration Authority | PKI component that verifies identities before the certificate authority issues certificates. | |
| RACE | Research and Development in Advanced Communications Technologies in Europe | European research program that produced the RIPEMD hash functions. | |
| RAD | Rapid Application Development | Software development approach emphasizing quick prototyping and iteration. | |
| RADIUS | Remote Authentication Dial-in User Service | Protocol for centralized authentication, authorization and accounting of network access. | RADIUS |
| RAID | Redundant Array of Inexpensive Disks | Combining multiple disks for redundancy or performance; now usually 'independent' disks. | RAID levels |
| RAS | Remote Access Server | Server that accepts connections from remote users and grants network access. | |
| RAT | Remote Access Trojan | Malware that gives an attacker hidden remote control of a system. | Malware types |
| RBAC | Role-based Access Control | Access control model where permissions are assigned to roles, and users get roles. | Identity and access management |
| RBAC | Rule-based Access Control | Access control model where access is decided by administrator-defined rules, like firewall ACLs. | Identity and access management |
| RC4 | Rivest Cipher version 4 | Stream cipher once used in WEP and SSL/TLS; now considered insecure. | Wireless security protocols |
| RDP | Remote Desktop Protocol | Microsoft protocol for remote graphical access to Windows systems over TCP 3389. | Port numbers reference |
| RFID | Radio Frequency Identifier | Wireless tags and readers used to identify objects or people; commonly radio-frequency identification. | |
| RIPEMD | RACE Integrity Primitives Evaluation Message Digest | Family of hash functions; RIPEMD-160 is the best-known version. | |
| ROI | Return on Investment | Measure of the benefit of an investment relative to its cost. | |
| RPO | Recovery Point Objective | Maximum acceptable amount of data loss, measured in time since the last backup. | Business continuity and disaster recovery |
| RSA | Rivest, Shamir, & Adleman | Widely used public-key algorithm for encryption and digital signatures, named for its inventors. | Symmetric vs asymmetric encryption |
| RTBH | Remotely Triggered Black Hole | Technique that drops attack traffic upstream by routing it to a null destination. | |
| RTO | Recovery Time Objective | Maximum acceptable time to restore a system after a disruption. | Business continuity and disaster recovery |
| RTOS | Real-time Operating System | Operating system that guarantees processing within strict time limits, common in embedded devices. | |
| RTP | Real-time Transport Protocol | Protocol that carries real-time audio and video, such as VoIP calls. | |
| S/MIME | Secure/Multipurpose Internet Mail Extensions | Standard for signing and encrypting email using certificates. | Email security (SPF, DKIM, DMARC) |
| SaaS | Software as a Service | Cloud model where the provider runs complete applications you use over the internet. | Cloud computing concepts |
| SAE | Simultaneous Authentication of Equals | Password-based key exchange used by WPA3-Personal; resists offline dictionary attacks. | Wireless security protocols |
| SAML | Security Assertions Markup Language | XML-based standard for exchanging authentication data for single sign-on; officially Security Assertion Markup Language. | Identity and access management |
| SAN | Storage Area Network | Dedicated high-speed network that provides block-level storage to servers. | |
| SAN | Subject Alternative Name | Certificate field listing additional hostnames or addresses the certificate covers. | PKI and digital certificates |
| SASE | Secure Access Service Edge | Cloud architecture combining SD-WAN with security services such as SWG, CASB and ZTNA. | Zero Trust |
| SCADA | Supervisory Control and Data Acquisition | Systems that remotely monitor and control industrial equipment across large areas. | |
| SCAP | Security Content Automation Protocol | NIST suite of specifications for automating vulnerability and configuration checks. | |
| SCEP | Simple Certificate Enrollment Protocol | Protocol that lets devices request and obtain certificates automatically. | Mobile device management (MDM) |
| SD-WAN | Software-defined Wide Area Network | WAN that uses software to route traffic across multiple connections such as broadband and MPLS. | WAN technologies |
| SDK | Software Development Kit | Set of tools and libraries for building software for a platform. | |
| SDLC | Software Development Lifecycle | Structured process for planning, building, testing and maintaining software. | Application security |
| SDLM | Software Development Lifecycle Methodology | The specific model used to run a software development lifecycle, such as waterfall or agile. | |
| SDN | Software-defined Networking | Network design that separates the control plane from the data plane for central management. | |
| SE Linux | Security-enhanced Linux | Linux kernel security module that enforces mandatory access control; usually written SELinux. | |
| SED | Self-encrypting Drives | Drive that encrypts data automatically in its own hardware. | |
| SEH | Structured Exception Handler | Windows mechanism for handling exceptions; overwriting it is a known exploit technique. | |
| SFTP | Secured File Transfer Protocol | File transfer over SSH; officially SSH File Transfer Protocol. | Port numbers reference |
| SHA | Secure Hashing Algorithm | Family of hash functions published by NIST, such as SHA-256; officially Secure Hash Algorithm. | Cryptography |
| SHTTP | Secure Hypertext Transfer Protocol | Obsolete alternative to HTTPS that encrypted individual messages; never widely adopted. | |
| SIEM | Security Information and Event Management | Platform that collects and correlates logs from many sources to detect and alert on threats. | SIEM |
| SIM | Subscriber Identity Module | Card that stores the subscriber's identity and keys for a mobile network. | Multi-factor authentication (MFA) |
| SLA | Service-level Agreement | Contract that defines measurable service levels, such as uptime, a provider must meet. | |
| SLE | Single Loss Expectancy | Expected cost of a single occurrence of a risk: asset value multiplied by exposure factor. | Risk management |
| SMB | Server Message Block | Windows file and printer sharing protocol, using TCP 445. | Port numbers reference |
| SMS | Short Message Service | Text messaging on mobile phones. | Multi-factor authentication (MFA) |
| SMTP | Simple Mail Transfer Protocol | Protocol for sending email between servers. | Port numbers reference |
| SMTPS | Simple Mail Transfer Protocol Secure | SMTP protected with TLS. | Port numbers reference |
| SNMP | Simple Network Management Protocol | Protocol for monitoring and managing network devices. | SNMP |
| SOAP | Simple Object Access Protocol | XML-based protocol for exchanging messages between web services. | |
| SOAR | Security Orchestration, Automation, Response | Tools that automate security workflows and incident response actions; usually Security Orchestration, Automation, and Response. | SIEM |
| SoC | System on Chip | Single chip that integrates a processor, memory and other components. | |
| SOC | Security Operations Center | Team and facility that monitor, detect and respond to security events. | Security operations centers (SOC) |
| SOW | Statement of Work | Document describing the specific work, deliverables and timeline for a project. | |
| SPF | Sender Policy Framework | DNS record listing which servers are allowed to send email for a domain. | Email security (SPF, DKIM, DMARC) |
| SPIM | Spam over Internet Messaging | Spam sent over instant messaging. | |
| SQL | Structured Query Language | Language for querying and managing relational databases. | |
| SQLi | SQL Injection | Attack that inserts malicious SQL into input to manipulate a database. | Application security |
| SRTP | Secure Real-Time Protocol | Profile of RTP that adds encryption and authentication to real-time media; officially Secure Real-time Transport Protocol. | |
| SSD | Solid State Drive | Storage device that uses flash memory with no moving parts. | Storage types (HDD, SSD, NVMe) |
| SSH | Secure Shell | Protocol for encrypted remote command-line access, using TCP 22. | SSH |
| SSL | Secure Sockets Layer | Deprecated predecessor of TLS for encrypting connections. | |
| SSO | Single Sign-on | One login that grants access to multiple applications. | Identity and access management |
| STIX | Structured Threat Information eXchange | Standard language for describing and sharing cyber threat intelligence. | Threat intelligence |
| SWG | Secure Web Gateway | Service that filters users' web traffic to enforce security policy. | Proxy servers |
| TACACS+ | Terminal Access Controller Access Control System | Cisco-developed AAA protocol on TCP 49 that obfuscates entire packet bodies; officially Terminal Access Controller Access-Control System Plus. | Authentication protocols (Kerberos, NTLM, RADIUS, TACACS+) |
| TAXII | Trusted Automated eXchange of Indicator Information | Protocol for exchanging STIX threat intelligence over HTTPS. | Threat intelligence |
| TCP/IP | Transmission Control Protocol/Internet Protocol | The protocol suite that underlies the internet. | The TCP/IP model |
| TGT | Ticket Granting Ticket | Kerberos ticket that lets an authenticated user request service tickets. | Kerberos |
| TKIP | Temporal Key Integrity Protocol | Legacy WPA encryption protocol built on RC4; now deprecated. | Wireless security protocols |
| TLS | Transport Layer Security | Protocol that encrypts and authenticates network connections, such as in HTTPS. | PKI and digital certificates |
| TOC | Time-of-check | Moment a program checks a condition; a race condition can exploit the gap before use. | |
| TOTP | Time-based One-time Password | One-time password generated from a shared secret and the current time. | Multi-factor authentication (MFA) |
| TOU | Time-of-use | Moment a program uses a resource after checking it; paired with time-of-check in race conditions. | |
| TPM | Trusted Platform Module | Hardware chip that securely stores keys and supports secure boot and disk encryption. | BIOS vs UEFI |
| TSIG | Transaction Signature | Mechanism that authenticates DNS transactions such as zone transfers using a shared secret. | |
| TTP | Tactics, Techniques, and Procedures | Description of how attackers operate, from high-level goals to specific methods. | Threat intelligence |
| UAT | User Acceptance Testing | Testing where end users confirm software meets their requirements before release. | |
| UAV | Unmanned Aerial Vehicle | Aircraft without a pilot on board, such as a drone. | |
| UBA | User Behavior Analytics | Analytics that baseline normal user behavior and flag anomalies. | |
| UDP | User Datagram Protocol | Connectionless transport protocol with no delivery guarantee, used where speed matters. | TCP vs UDP |
| UEFI | Unified Extensible Firmware Interface | Modern firmware interface that replaced BIOS and supports Secure Boot. | BIOS vs UEFI |
| UEM | Unified Endpoint Management | Management of all endpoint types, including desktops and mobile devices, from one platform. | Mobile device management (MDM) |
| UPS | Uninterruptible Power Supply | Battery backup that keeps equipment powered during short outages. | Physical security controls |
| URI | Uniform Resource Identifier | String that identifies a resource, such as a URL. | |
| URL | Universal Resource Locator | Web address that locates a resource; officially Uniform Resource Locator. | |
| USB | Universal Serial Bus | Standard interface for connecting peripherals and storage to computers. | PC hardware components |
| USB OTG | USB On the Go | USB feature that lets a mobile device act as a host for peripherals such as flash drives. | |
| UTM | Unified Threat Management | Single appliance combining firewall, intrusion prevention, antivirus and other security functions. | |
| UTP | Unshielded Twisted Pair | Common copper network cable without shielding, such as Cat 6. | Network cable types |
| VBA | Visual Basic | Visual Basic for Applications (VBA), the scripting language in Microsoft Office macros, abused by macro malware. | |
| VDE | Virtual Desktop Environment | Virtual desktop provided to users from a central system. | |
| VDI | Virtual Desktop Infrastructure | Hosting desktop operating systems on central servers and delivering them to users remotely. | |
| VLAN | Virtual Local Area Network | Logical network segment created on switches to separate traffic. | VLANs |
| VLSM | Variable Length Subnet Masking | Subnetting technique that uses different mask lengths within one network. | Subnetting |
| VM | Virtual Machine | Software-emulated computer running on a hypervisor. | Virtualization and hypervisors |
| VoIP | Voice over IP | Phone calls carried over IP networks. | Quality of service (QoS) |
| VPC | Virtual Private Cloud | Isolated virtual network within a public cloud. | |
| VPN | Virtual Private Network | Encrypted tunnel that extends a private network over a public one. | VPNs |
| VTC | Video Teleconferencing | Video conferencing between multiple locations. | |
| WAF | Web Application Firewall | Firewall that inspects HTTP traffic to block web application attacks such as SQL injection. | Firewall types |
| WAP | Wireless Access Point | Device that provides wireless network access; same role as an AP. | Wireless networking |
| WEP | Wired Equivalent Privacy | Original Wi-Fi encryption using RC4; broken and should not be used. | Wireless security protocols |
| WIDS | Wireless Intrusion Detection System | System that monitors the wireless spectrum for rogue access points and attacks. | Wireless networking |
| WIPS | Wireless Intrusion Prevention System | System that detects and blocks wireless threats such as rogue access points. | Wireless networking |
| WO | Work Order | Document authorizing a specific task or job. | |
| WPA | Wi-Fi Protected Access | Wi-Fi security standard family; WPA2 and WPA3 are the current versions. | Wireless security protocols |
| WPS | Wi-Fi Protected Setup | Feature for easy Wi-Fi device setup; its PIN method is vulnerable to brute force. | Wireless security protocols |
| WTLS | Wireless TLS | Wireless Transport Layer Security: TLS-based security for the Wireless Application Protocol (WAP) used by early mobile phones; now obsolete. | |
| XDR | Extended Detection and Response | Detection and response that correlates data across endpoints, network, cloud and email. | Endpoint detection and response (EDR) |
| XML | Extensible Markup Language | Markup language for storing and exchanging structured data. | |
| XOR | Exclusive Or | Bitwise operation that outputs 1 when inputs differ; used throughout cryptography. | |
| XSRF | Cross-site Request Forgery | Another abbreviation for cross-site request forgery (CSRF). | Application security |
| XSS | Cross-site Scripting | Attack that injects malicious scripts into web pages viewed by other users. | Application security |
Related Security+ Articles
Preparing for Security+?
See the books, practice exams, and free resources that actually work.