List of information technology initialisms
The table below lists information technology initialisms and acronyms in common and current usage. These acronyms are used to discuss LAN, internet, WAN, routing and switching protocols, and their applicable organizations. The table contains only current, common, non-proprietary initialisms that are specific to information technology. Most of these initialisms appear in IT career certification exams.
| Acronym | Meaning | Primary Applicability | Normative Reference |
| ACK | Acknowledgement | Transport and other layers | TCP/IP, for example. RFC 793 |
| ACL | Access control list | Security, application layer | Access control list, |
| ADSL | Asymmetric digital subscriber line | Telecom | , for example |
| AES | Advanced Encryption Standard | Security | |
| ANSI | American National Standards Institute | Organization | |
| API | Application Programming Interface | Software | |
| ARP | Address Resolution Protocol | Link layer | RFC 1122 |
| ATM | Asynchronous Transfer Mode | Telecom | |
| BGP | Border Gateway Protocol | Application layer, Routers | RFC 4271 |
| BSS | Basic service set | Wireless | |
| CAT | Category | Physical layer | |
| CCITT | Standards organization that has been replaced by ITU-T | Organization | |
| CHAP | Challenge-Handshake Authentication Protocol | Security, telecom | RFC 1994 |
| CIDR | Classless Inter-Domain Routing | Architecture | RFC 1518 RFC 1519 |
| CIR | Committed Information Rate | Telecom | RFC 1490 RFC 1973 RFC 2427 |
| CLI | Command line interpreter | Hardware | , for example |
| CPE | Customer premises equipment | Telecom | |
| CPU | Central processing Unit | Microprocessor | Wikipedia |
| CRC | Cyclic redundancy check | Link and other layers | 24 References here. |
| CRC-16-CCITT | Cyclic redundancy check | Link layers | Reference on CRC page. |
| CRT | Cathode Ray Tube | Television set, Computer Monitor | Cathode ray tube |
| CSMA/CA | Carrier sense multiple access / collision avoidance | Wireless | |
| CSMA/CD | Carrier sense multiple access / collision detection | Physical layer | |
| CSU/DSU | Channel service unit / data service unit | Telecom | |
| CMOS | Complementary metal-oxide semiconductor | Utillity | Wikipedia |
| DAM | Database activity monitoring | Security | Wikipedia |
| DAM | Digital asset management | Internet Layer | Wikipedia |
| DCE | Data communications equipment | Telecom | - |
| DEC | Digital Equipment Corporation | Organization | Purchased by Compaq in 1998. Merged with Hewlett-Packard 2002. |
| DES | Data Encryption Standard | Security | |
| DHCP | Dynamic Host Configuration Protocol | Application layer, Internet Layer | RFC 2131 and others |
| DNS | Domain Name System | Application layer | Over 30 RFCs here. |
| DRAM | Dynamic random-access memory | Hardware | |
| DSL | Digital subscriber line | Telecom | |
| DSLAM | Digital subscriber line access multiplexer | Telecom | |
| DTE | Data Terminal Equipment | Telecom | |
| DMI | Desktop Management Interface | Utillity | Wikipedia |
| EHA | Ethernet Hardware Address | Link layer | |
| EIA | Electronics Industry Alliance | Organization | |
| EIGRP | Enhanced Interior Gateway Routing Protocol | Internet Layer | |
| EOF | End Of Frame | Link layer | HDLC framing |
| ESS | Extended service set | Wireless | |
| FCC | Federal Communications Commission | Organization | |
| FCS | Frame check sequence | Link layer | Ethernet Frame |
| FDDI | Fiber Distributed Data Interface | Link layer | X3T9.5, |
| FTP | File Transfer Protocol | Application layer | RFC 959 and others |
| GBIC | Gigabit interface converter | Hardware | |
| gbps | Gigabit per second | Physical layer | Gigabit per second |
| GEPOF | Gigabit Ethernet Plastic Optical Fiber | Physical layer | IEEE P802.3bv |
| HDLC | High-level Data Link Control | Link layer | |
| HTTP | HyperText Transfer Protocol | Application layer | |
| HTTPS | HyperText Transfer Protocol Secure | Transport and other layers | |
| IANA | Internet Assigned Number Authority | Organization | |
| ICaaS | Integration Capability as a Service | Organization | |
| ICMP | Internet Control Message Protocol | Internet Layer | RFC 792 |
| IDF | Intermediate distribution frame | Physical layer | Structured cabling or |
| IDS | Intrusion Detection | - | - |
| IEEE | Institute for Electrical and Electronic Engineers | Organization | |
| IETF | Internet Engineering Task Force | Organization | |
| IMAP | Internet Message Access Protocol | Application layer | RFC 3501 |
| IP | Internet Protocol | Internet Layer | RFC 791 RFC 1606 |
| IPS | Intrusion prevention system | Security | |
| IS-IS | Intermediate System to Intermediate System | Internet Layer | |
| ISDN | Integrated Services Digital Network | Telecom | |
| ISP | Internet service provider | Telecom | |
| ITU-T | International Telecommunications Union | Organization | http://www.itu.int |
| kbps | Kilobit per second | Physical layer | Kilobit_per_second |
| LACP | Link Aggregation Control Protocol | Data link layer | |
| LAN | Local area network | Link and other layers | |
| LAPB | Link Access Procedure, Balanced | Telecom | |
| LAPF | Link-access procedure for frame relay | Telecom | RFC 1490 |
| LLC | Logical link control | Link layer | |
| MAC | Media access control | Link layer | and , for example |
| MAM | Media access management | Internet layer | Wikipedia |
| MAN | Metropolitan area network | Telecom | |
| Mbps | Megabits per second | Physical layer | Megabit_per_second |
| MC | Multiple choice | IT Professional Certification | |
| MDF | Main distribution frame | Physical layer | See also Structured cabling |
| MIB | Management information base | Application layer | RFC 3418 |
| MoCA | Multimedia over Coax Alliance | Organization | |
| MPLS | Multiprotocol Label Switching | network technology | |
| MTU | Maximum Transmission Unit | Multiple layers | |
| NAC | Network access control | Link and other layers | |
| NAT | Network Address Translation | Internet Layer | |
| NBMA | Non-Broadcast Multiple Access | Telecom | See ATM, Frame Relay and X.25, for examples. |
| NIC | Network Interface Card | Physical layer | |
| NRZ | Non-return-to-zero | Physical layer | |
| NRZI | Non-return to zero inverted | Physical layer | |
| NVRAM | Non-volatile RAM | Hardware | Sample vendor data |
| OSI | Open System Interconnect | Organization | Open Systems Interconnection Protocol Specifications |
| OSPF | Open Shortest Path First | Internet Layer | RFC 2238 |
| OUI | Organization Unique Identifier | Link and other layers | |
| PAP | Password authentication protocol | Security | RFC 1334 |
| PAT | Port address translation | Internet Layer | RFC 1918 |
| PC | Personal computer | Hardware | - |
| PIM | Personal information manager | Software category | - |
| PIM | Privileged Identity Management | Software category | - |
| PCM | Pulse-code modulation | Physical layer | |
| PDU | Protocol data unit | Multiple layers | |
| POP3 | Post Office Protocol, version 3 | Application layer | RFC 1939 |
| POP | Point of presence | Telecom | |
| POST | Power-on self test | Hardware | , for example |
| POTS | Plain old telephone service | Telecom | |
| PPP | Point-to-point Protocol | Telecom | RFC 1661 |
| PPTP | Point-to-Point Tunneling Protocol | Telecom | RFC 2637 |
| PTT | Public Telephone and Telegraph | Telecom | or |
| PVST | Per-VLAN Spanning Tree | Link layer | |
| RADIUS | Remote Authentication Dial-In User Service | Security | RFC 2865 |
| RAM | Random Access Memory | Physical layer | |
| RARP | Reverse ARP | Link layer | RFC 903 |
| RFC | Request for Comments | Multiple layers | |
| RIP | Routing Information Protocol | Internet Layer | RFC 2453, for RIP version 2 |
| RLL | Run-Length Limited | Physical layer | RLL is used in a wide range of encodings. |
| ROM | Read-Only Memory | Hardware | |
| RSTP | Rapid Spanning Tree Protocol | Link layer | - Rapid Reconfiguration of Spanning Tree |
| RTP | Real-time Transport Protocol | Application layer | RFC 3550 |
| RCP | Royal College of Physicians | Gibson layer | RFC 69 |
| SDLC | Synchronous Data Link Control | Link layer | |
| SDN | Software Defined Networking | Architecture | Software-defined networking |
| SFD | Start-of-frame delimiter | Link layer | , or RFC 2687, for examples |
| SFP | Small form-factor pluggable | Hardware | |
| S-HTTP | Secure HTTP | Transport and other layers | RFC 2660 See also https |
| SLARP | Serial Line ARP | Link and other layers | |
| SLIP | Serial Line Internet Protocol | Telecom | RFC 1055 |
| SMTP | Simple Mail Transfer Protocol | Application layer | RFC 5321 |
| SNA | Systems Network Architecture | Multiple layers | |
| SNAP | SubNet Access Protocol | Link layer | |
| SNMP | Simple Network Management Protocol | Application layer | RFC 1155, RFC 3410 thru RFC 3418 and others |
| SOF | Start of frame | Link layer | , or RFC 2687, for examples |
| SRAM | Static random access memory | Hardware | |
| SSH | Secure shell | Application layer | RFC 4252 |
| SSID | Service set identifier | Wireless | |
| STP | Spanning Tree Protocol | Link layer | |
| SYN | Synchronization | Link and other layers | RFC 793 and many others |
| TCP/IP | Transmission Control Protocol/Internet Protocol | Transport layer | RFC 793 and many others |
| TDM | Time-division multiplexing | Physical layer | |
| TFTP | Trivial File Transfer Protocol | Application layer | RFC 1350 |
| TIA | Telecommunications Industry Alliance | Organization | |
| TOFU | Trust On First Use | Security | |
| UDP | User Datagram Protocol | Transport layer | RFC 768 |
| USB | Universal Serial Bus | Physical and other layers | |
| UTP | Unshielded twisted pair | Physical | Many versions are defined by TIA, such as: |
| VC | Virtual circuit | Transport and other layers | |
| VLAN | Virtual local area network | Link layer | |
| VLSM | Variable-length subnet masking | Architecture | RFC 1518 RFC 1519 |
| VPN | Virtual private network | Application layer | |
| W3C | World Wide Web Consortium | Organization | |
| WAN | Wide-area network | Telecom | |
| WEP | Wired Equivalent Privacy | Wireless | |
| Wi-Fi | IEEE 802.11 | Wireless | |
| WPA | Wi-Fi Protected Access | Security | |
| www | World Wide Web | Architecture |