- T&C Terms & Conditions
- TA Terminal Adapter
- TAC Terminal Access Controller
- TANSTAAFL There Ain't No Such Thing As A Free Lunch
- TAP Telelocator Alphanumeric Protocol / Technological Assistance Program
- TAPI Telephony Application Programming Interface
- tar tape archiver
- TB TeraByte / Transparent Bridging
- TCB Transmission Control Block
- TCL Tool Command Language
- TCP/IP Transmission Control Protocol/Internet Protocol
- TDM Time Division Multiplexing
- TDMA Time Division Multiple Access
- TDP Telelocator Data Protocol
- telnet telecommunications network
- TEMPEST Transient ElectroMagnetic Pulse Emanation STandard
- TFT Thin Film Transistor
- TFTP Trivial File Transfer Protocol
- TG Technical Guide
- TH Transmission Header
- TI Texas Instruments
- TIA Telecommunications Industry Association
- TIC Token Ring Interface Coupling
- TIFF Tag Image File Format
- TIMS Transmission Impairment Measurement Set
- TIRPC Transport-Independent Remote Procedure Call
- TLA Three-Letter Acronym
- TLAP TokenTalk Link Access Protocol
- TLI Transport Layer Interface
- TMC Thinking Machines Corporation
- TN Twisted Nematic
- TP Transaction Processing / Transport Protocol
- TQM Total Quality Management
- TR Terminal Resistors / Terminal Ready
- trn threaded readnews
- TRS Tandy Radio Shack
- TRSDOS Tandy Radio Shack Data Operating System
- TSA Target Service Agents
- TSR Terminate and Stay Resident
- TSS Task State Segment
- TTA Transport Triggered Architecture
- TTF True Type Font
- TTFN Ta Ta For Now
- TTL Time To Live
- TTY TeleTYpewriter