| tfam | PLINK Individual Information File |
| tfh | Borland Turbo Profiler Help Data |
| tfl | Tific Client Data |
| tfv | YETI Vegetation Plot Database Export File |
| tfx | Avid Pro Tools Eleven Rack Presets |
| tfz | FBS Vehicle Database |
| tgc | Terragen Clip File |
| tgd | Terragen 2 World |
| tgf | libigl Control Handle Graphs |
| tgf | Stonevoice Translator Tag Data |
| tgl | SkyMap Target Lists |
| tgmd | WDTV ThumbGen Movie Metadata |
| tgmg | TabGroups Manager for Firefox Exported Group Data |
| tgo | Terragen Object File |
| tgp | FM-ONE Target Protocol Data |
| tgs | GSTree Tree Data |
| tgw | FM-ONE Target Write-in Control Data |
| tgw | Terragen World |
| tgworld | Terragen World |
| th | Therion Data |
| th2 | Therion TH2 Map |
| tha | Thunderbird MoreFunctionsForAddressBook Add-on Data |
| the | Microsoft Plus! Theme File |
| theme | Microsoft Windows Desktop Theme |
| themepack | Microsoft Windows 7 Theme Pack |
| thf | LS-DYNA Time History Database |
| thm | Thunderbird MoreFunctionsForAddressBook Mailing Lists Data |
| thp | Intuit TurboTax Tax Line Description |
| ths | Corel WordPerfect Thesaurus Dictionary |
| thu | THUNDER Data |
| thumbdata | Android Thumbnail Data |
| thumbnail | Android Thumbnail Cache Data |
| thumbsdb | PixFiler Thumbnail Database |
| tia | Siemens TIA Portal Data File |
| tic | ArcInfo Coverage TIC |