| .t | Turing Programming Language Format |
| .t$2a | Timbuktu Pro |
| .t$ab | Timbuktu Pro Address Book |
| .t$m | AVG Internet Security Temporary Format |
| .t00 | TaxCut Federal Data |
| .t01 | TAXWIZ Deluxe Tax Format |
| .t02 | TaxCut 2002 Tax Return Format |
| .t03 | TaxCut 2003 Tax Return Format |
| .t04 | TaxCut 2004 Tax Return Format |
| .t05 | TaxCut 2005 Tax Return Format |
| .t06 | TaxCut 2006 Tax Return Format |
| .t07 | TaxCut 2007 Tax Return Format |
| .t08 | TaxCut 2008 Tax Return Format |
| .t09 | At Home 2009 Tax Return Format |
| .t1 | Male MRI Image Format |
| .t10 | At Home 2010 Tax Return Format |
| .t11 | At Home 2011 Tax Return Format |
| .t12 | H&R Block At Home 2012 Tax Return Format |
| .t13 | H&R Block Tax Software Tax Return |
| .t16 | DAMASK |
| .t2 | TrueType Font Format |
| .t2b | CyBook Thumbnail Image Format |
| .t2d | Technology Transfer Database |
| .t2k | Teach2000 Document Format |
| .t2ks | Teach2000 Exam Results Format |
| .t2kt | Teach2000 Exam Format |
| .t2s | Tier2 |
| .t2t | Txt2tags Text Document |
| .t3 | TADS 3 Game |
| .t3001 | TARGET 3001! Circuit Design Project Format |
| .t32 | Drive Image 5 |
| .t3a | Swift 3D Animation Preset |
| .t3d | Epic Unreal Engine 3D Object Format |
| .t3v | TADS 3 Saved Position |
| .t3x | TYPO3 Compressed Extension |
| .t4 | TerrAlign Alignment Configuration |
| .t44 | DBASE IV Temporary |
| .t49 | HP48/HP49 Specific |
| .t64 | Commodore 64 Emulator Tape Format |
| .t65 | Adobe PageMaker Template |
| .t80 | TANK - API 650/653 Output Document |
| .ta1 | TaxACT 2001 Tax Form |
| .ta9 | TaxACT Tax Document |
| .taac | Sun TAAC Bitmap Image Format |
| .tab | MapInfo Format |
| .tabula-buttons | Tabula Button Library |
| .tabula-doc | Tabula Document |
| .tabula-docstyle | Tabula Document Settings |
| .tac | ActiCalc Data Format |
| .tad | Total Annihilation Demo Saved Game Data |
| .taf | ADRIFT Text Adventure Format |
| .tag | DataFlex Query Tag Name Format |
| .tah | Turbo Assembler Help |
| .tak | TAK Lossless Compressed Audio Format |
| .tal | BrainVoyager QX Talairach Coordinate |
| .tam | Tame Program Settings |
| .tan | Amazon Kindle |
| .tao | Track At Once CD/DVD Image |
| .tap | Commodore 64 Cassette Tape Image |
| .tar | Unix Standard Archive Format, Tape Archive |
| .tar-gz | Gzip Compressed TAR Archive |
| .tar-lzma | TAR Archive |
| .tar-z | TAR Compressed Archive |
| .tar.gz | Compressed Tarball File |
| .tar.gz2 | Misnamed BZ2 Tarball |
| .tar.lzma | LZMA Compressed Tarball |
| .tar.xz | XZ Compressed TAR Archive Format |
| .tar.z | Tar.Z Compressed Archive |
| .taraa | Linux TAR Split Archive |
| .tardist | Tardist Compressed Archive |
| .targa | Truevision TarGA Bitmap Image |
| .targets | MSBuild Targets Format |
| .tas | ADRIFT Text Adventure Save |
| .tat | ESRI Geographic Text Attribute Table |
| .tax | TurboTax Tax Return Format |
| .tax08 | TurboTax 2008 Tax Return Format |
| .tax09 | TurboTax 2009 Tax Return Format |
| .tax10 | TurboTax 2010 Tax Return Format |
| .tax11 | TurboTax 2011 Tax Return Format |
| .tax12 | TurboTax 2012 Tax Return Format |
| .tax13 | TurboTax Tax Return |
| .tax2008 | TurboTax 2008 Tax Return Format |
| .tax2009 | TurboTax 2009 Tax Return Format |
| .tax2010 | TurboTax 2010 Tax Return Format |
| .tax2011 | TurboTax 2011 Tax Return Format |
| .tax2012 | TurboTax 2012 Tax Return Format |
| .tax2013 | TurboTax Tax Return |
| .taxform | QuickBooks Draft |
| .taz | TAR Compressed Archive |
| .tb | Tabbery Tab Format |
| .tb0 | Adobe Photoshop Format Browser Thumbnail Cache Format |
| .tb1 | Borland Turbo C Font |
| .tb2 | Borland Turbo C Font |
| .tb3 | Intel VTune Performance Monitor Sampling Data |
| .tb5 | Intel VTune Performance Monitor Sampling Data |
| .tba | DB/Text Database Primary Textbase Definition |
| .tbb | The Bat! E-mail Hives |
| .tbc | Formula 1 Car Race 2001 Season01 Vehicles |
| .tbd | Document System Document Source Code |
| .tbe | TMPGEnc List |
| .tbf | Trellian Button Factory |
| .tbg | Infinity Engine Game |
| .tbi | FIFA 2001 Data Cmn Be |
| .tbk | ToolBooK Format |
| .tbl | Table Format |
| .tbm | DB/TextWorks Database Menu Screen |
| .tbn | XBMC Folder Thumnail Format |
| .tbp | TASBooks Accounting Data Format |
| .tbr | SoftQuad XMetaL Configuration |
| .tbs | TuneUp Style Boot Screen Format |
| .tbt | Timbuktu Pro Remote Control Software |
| .tbv | Turbo-BrainVoyager Data |
| .tbx | Trados Glossary |
| .tbz | Bzip2 Compressed TAR Archive Format |
| .tbz2 | BZIP/TAR Compressed Archive Format |
| .tc | TrueCrypt Disk Volume Format |
| .tc2 | TurboCAD 2D Drawing Format |
| .tc3 | TurboCAD 2D/3D Mac Drawing Format |
| .tca | The Complete Animator Animation |
| .tcb | Tokyo Cabinet TBZIP |
| .tcc | TimeCalc Classic Proprietary Formatted Data File Format |
| .tcd | Technobox CAD Drawing |
| .tce | TLE File Format |
| .tcf | TTWin 3 Certificate Licensing |
| .tch | Borland C++ Help |
| .tcl | TCL Script Source Code |
| .tclog | TestComplete Log |
| .tcm | TurboCAD Mac Drawing Format |
| .tcp | Tally.ERP Compiled Program Format |
| .tcr | Psion Series 3 EBook Format |
| .tcs | TreeComp Snapshot |
| .tcsh | Unix Shell Script |
| .tct | TurboCAD Template Format |
| .tcw | TurboCAD For Windows Drawing Format |
| .tcx | Garmin Training Center Database XML Format |
| .tcz | PSTextMerge Script Format |
| .tczl | Tiny Core Linux Xlib |
| .td | Borland Turbo Debugger For DOS Configuration Format |
| .td0 | Teledisk Disk Image |
| .td2 | Borland Turbo Debugger For Win32 Configuration |
| .td4 | RollerCoaster Tycoon Track Design Format |
| .td6 | RollerCoaster Tycoon Track Design Format |
| .tda | Palm To Do Format |
| .tda3mt | DivX Author Template Format |
| .tdat | Codewarrior Mac |
| .tdb | EBay Turbo Lister Format |
| .tdc | ALLCapture Project |
| .tddd | 3D Data Description Format |
| .tde | Tableau Data Extract Format |
| .tdf | Total Annihilation Features Format |
| .tdi | Explore (TDI) & Maya Image File (IFF Format) |
| .tdim | Digital F/X Image Format |
| .tdk | Borland Turbo Debugger Keystroke Recording |
| .tdl | Tab Delineated File Format |
| .tdlog | Microsoft Visual Studio |
| .tdm | LabVIEW Binary Measurement Format |
| .tdmb | Trimble Outdoors Navigator Map Bundle |
| .tdms | LabVIEW TDMS |
| .tdms_index | LabVIEW |
| .tdoc | Tabula Document |
| .tdp | Sherif DrawPlus Thumbnail |
| .tdr | Top Draw Vector Graphic |
| .tds | Borland Turbo Debugger Symbol Table Format |
| .tdt | THOR Data Tree Format |
| .tdt2 | Panasonic HD Video Camera Movie |
| .tdv | DIAdem VIEW Module Setup Information |
| .tdx | Visual FoxPro Offline View |
| .tdy | TODAY BuildProfessional Application |
| .tdz | Drobo Firmware Update Format |
| .te | Textease CT Database Format |
| .te3 | Wintrack Object Format |
| .tea | Tea Source |
| .teacher | SMART Response Teacher Database Format |
| .tec | Tecplot ASCII Data Format |
| .ted | Tribes 2 Game Format |
| .tee | TeeChart Office Graphics |
| .tef | TablEdit Tablature Format |
| .tei | TrackEye Image Sequence |
| .tem | Borland C++ Turbo Editor Macro Language Script |
| .temp | Temporary Format |
| .template | Template Format |
| .TemporaryItems | Mac OS X Temporary |
| .ten | TeeChart For .NET Chart Control Template |
| .tep | TopiaryExplorer Project |
| .teq | Saia S-Web-Editor PCD |
| .ter | TerraGen Landscape |
| .term | Apple Mac OS X Terminal |
| .terminal | Apple Mac OS X Terminal Settings Format |
| .terms | Cygwin Demos |
| .terrain | TerraGen Terrain Graphic Data |
| .tes | TECO Macro |
| .testrunconfig | Microsoft Visual Studio Test Run Configuration Format |
| .testsettings | Microsoft Visual Studio Format |
| .tet | Textease Template Format |
| .tew | Wrestling Spirit |
| .tex | TeX/LaTeX Text Document Format |
| .tex0 | Nintendo Wii Texture Format |
| .texi | TEX |
| .texinfo | Texinfo Source |
| .text | Simple Text Format |
| .textclipping | Mac OS X Text Clipping Format |
| .TextExpander | TextExpander |
| .textfactory | BBEdit Text Factory |
| .textile | Eclipse IDE WikiText Document |
| .textmate_init | Unix Shell Script (bash) |
| .texts | Ribbons Texts |
| .texturepack | Arena Wars Texture Pack |
| .textutils | Gnome Desktop |
| .tf | Autodesk Inventor Transcript |
| .tf2 | Team Fortress 2 Data |
| .tfa | Turbo Profiler Area Format |
| .tfc | Unreal Engine 3 Texture Cache Format |
| .tfd | Tape Format Requirements Document Format |
| .tff | IDOLON Tagged |
| .tfh | Turbo Profiler Help |
| .tfil | Blizzard Software Update Format |
| .tfl | Tific Client |
| .tfm | Tagged Font Metric Format |
| .tfmx | Final Musicsystem EXtended Amiga Audio Format |
| .tfp | ProWORX Nxt Full Page Data |
| .tfr | Star Wars Tie Fighter Game Pilot Format |
| .tfrd | Tape Image Format Requirements Document |
| .tfs | Turbo Profiler Statistical Information |
| .tft | Text Formatter Plus Text Information |
| .tfw | World File For TIFF |
| .tfwx | ArcGIS Approximate Affine Transformation |
| .tfx | Tax Exchange |
| .tg | Gzip Compressed TAR Archive |
| .tg4 | TG4 Image Format |
| .tga | Truevision TarGA Bitmap Image |
| .tgb | IPSec VPN Client VPN Configuration |
| .tgc | Terragen Node Clip |
| .tgd | TerraGen World |
| .tgf | Trival Graph Format |
| .tgh | Guitar Hero 3 Tier Settings |
| .tgi | SimCity 4 |
| .tgl | SkyMap Pro Target List |
| .tgmd | ThumbGen Movie Metadata |
| .tgmg | TabGroups Manager For Firefox Exported Group |
| .tgml | Tecumseh Group Markup Language |
| .tgo | Terragen 2 Object |
| .tgp | TGPGuiLib Terragen Plugin |
| .tgq | Dungeon Keeper 2 Movie Game |
| .tgs | GSTree Phylogenetic Tree Information |
| .tgv | Electronic Arts Video |
| .tgw | TerraGen World |
| .tgworld | TerraGen World |
| .tgx | Stronghold |
| .tgz | Gzip Compressed TAR Archive |
| .th | Therion Data Format |
| .tha | Windows Thai Noise-Words List Format |
| .thb | KinuPix Skin |
| .thd | Dolby TrueHD Audio |
| .the | Microsoft Plus! Pack Desktop Theme |
| .theater | IMovie Theater Library |
| .them | Microsoft Windows Desktop Theme |
| .theme | Windows Desktop Theme Format |
| .themepack | Microsoft Windows 7 Theme Pack Format |
| .thewitchersave | The Witcher Save Game |
| .thf | PcAnywhere Thin Host |
| .thl | PowerProducer Background Image Icon |
| .thm | Sony Ericsson Mobile Phone Theme Format |
| .thme | Microsoft Theme Format |
| .thmx | Microsoft Office 2007/2010 Theme Format |
| .thn | Graphics Workshop For Windows Thumbnail |
| .thnl | Graphics Workshop For Windows Thumbnail |
| .thp | TurboTax Text String Format |
| .thr | Thred Embroidery Outline |
| .ths | Corel WordPerfect Thesaurus Dictionary |
| .thumb | JAlbum Thumbnail Format |
| .thumbdata | Google Android Thumbnail Database |
| .thumbdata-idx3 | Android Thumbnail Index |
| .thumbdata3 | Google Android Thumbnail Database |
| .thumbdata3--1763508120 | Android Thumbnail Index |
| .thumbdata3--1967290299 | Android Thumbnail Index |
| .thumbdata3--number | Android MediaProvider Thumbnail Database |
| .thumbdata4 | Google Android Thumbnail Database |
| .thumbdata4--1763508120 | Android Thumbnail Index |
| .thumbdata4--1967290299 | Android Thumbnail Index |
| .thumbdata5 | Google Android Thumbnail Database |
| .thumbdata5--1763508120_0 | Android Thumbnail Index |
| .thumbdata5--1967290299_0 | Android Thumbnail Index |
| .thumbsdb | PixFiler Thumbnail Database |
| .thx | Amiga THX Tracker Music |
| .ti | Timber Compiler |
| .ti0 | Tabula Binary Settings And Initialization |
| .ti1 | Tabula Binary Settings And Initialization |
| .ti2 | Tabula Binary Settings And Initialization |
| .tib | Acronis TrueImage Backup Disk Image Format |
| .tic | TruKnox Cache |
| .tid | TruKnox Transfer Details |
| .tie | CrossTie Installer Format |
| .tif | Aldus Tagged Image File Format (TIFF) Bitmap Image |
| .tiff | Aldus Tagged Image File Format (TIFF) Bitmap Image |
| .tig | Texas Instruments Connect Backup Format |
| .tiger | Crystal Dynamics Game Data Archive Format |
| .tii | Apache Lucene Term Info Index |
| .tikz | Matlab Tikz Script |
| .til | Nova Logic Game Tile |
| .tile | Eclipse Image |
| .tilemap | XML Tilemap Format |
| .TileSkinZip | Elemental Tile Skin |
| .tim | The Incredible Machine Level Format |
| .time | LIGHT Format |
| .tin | Bentley GEOPAK Environmental Modeling Systems |
| .tinf | Microsoft Theme Info |
| .tiny | Gnome Desktop |
| .tinyid | Tiny Village |
| .tip | TuneUp Utilities Icon Package Format |
| .tiprogram | TI-Basic Source Code Format |
| .tir | Tibia RePlay Tibia Movie |
| .tis | TruKnox Captured Device Settings Format |
| .tit | Train Simulator Track Interactive Table |
| .tivo | TiVo Video Format |
| .tiw | Bentley InRoads |
| .tix | DivX Video Download Activation Format |
| .tja | Taikojiro Song Map Format |
| .tjc | Taikojiro Song Map Sequence Format |
| .tjf | IBM Rational ClearCase Transaction |
| .tjp | TaskJuggler Project Format |
| .tk | Tk Language Script |
| .tk1 | Wintec Tools GPS Log |
| .tk2 | Roxio/Take Two Backup |
| .tk3 | TK3 Multimedia EBook Format |
| .tkb | TicketBench Data |
| .tkfl | TKLinks Saver Favorite Links Format |
| .tkl | Takeoff Live PDF Working Data |
| .tkm | TkMOO-light |
| .tkn | Liberty BASIC Application Distribution |
| .tko | Win32/Oficla Malware Format |
| .tkp | MicroImages SML Script Standalone Application |
| .tkr | ESignal Ticker Format |
| .tks | Traktor Pro MIDI Map |
| .tkw | TK Solver |
| .tl | OpenTL Open Track List |
| .tl5 | Timeliner 5 Format |
| .tla | TuneUp Logo Animations |
| .tlb | OLE Type Library |
| .tlbackup | True Launch Bar Backup Settings |
| .tlc | The Logo Creator Format |
| .tld | Tag Library Descriptor Format |
| .tle | TLE File Format |
| .tlg | QuickBooks Transaction Log Format |
| .tlh | Typelib Generated C/C++ Header Format |
| .tli | Typelib Generated C/C++ Inline Format |
| .tlic | Trust Lincense |
| .tlk | BioWare Talk Table Format |
| .tll | LG TV Link-Loader Configuration Format |
| .tlm | Timeline Maker Timeline |
| .tlo | SPSS User Table Lookup Format |
| .tlp | Microsoft TimeLine Project |
| .tlq | Art Explosion T-Shirt Factory Deluxe |
| .tlr | Tableau Offline License Registration |
| .tls | TuneUp Utilities Logon Screen Format |
| .tlt | Trellix Web Design |
| .tlv | TruLASER View Geometry Data |
| .tlx | Wintertree Dictionary Format |
| .tly | Adobe Photoshop Elements Backup Catalog |
| .tlz | Unix TLZ Compression Engine Format |
| .tlzma | LZMA Compressed Tar Archive |
| .tm | TeXmacs Document |
| .tm1 | TimeWise |
| .tm2 | Playstation 2 TIM2 Bitmap Format |
| .tm8 | TMC Audio Format |
| .tmb | Timbuktu Pro Connection Document Format |
| .tmbundle | TextMate Bundle Format |
| .tmc | Unknown File Extension |
| .tmd | TextMaker Document Format |
| .tmdb | TaskMerlin Database |
| .tme | Bryce Animation Time Curve Format |
| .tmf | Corel WordPerfect Tagged Font Metric |
| .tmh | Trace Message Header |
| .tmi | Thin Client Media-3 Encoded Video |
| .tmk | Turbo Pascal Tour |
| .tml | PADGen |
| .tmlanguage | TextMate Grammar Format |
| .tmm | TimeMap Metadata |
| .tmo | 3D Custom Girl Animation Format |
| .tmp | Temporary Format |
| .tmpl | SWISH-E Example Format |
| .tmpreferences | TextMate Preference |
| .tmproj | TextMate Project Format |
| .tmproject | TextMate Project |
| .tmprtf | TimeMap Portable |
| .tmq | TestMaster |
| .tmr | Apimac Timer Settings Format |
| .tms | Timeless Time & Expense Multi-user Settings Format |
| .tmtheme | TextMate Theme Format |
| .tmv | TextMaker Document Template Format |
| .tmvt | TimeMap Template |
| .tmw | Timeless Time & Expense Multi-user Security Format |
| .tmx | Translation Memory EXchange Format |
| .tmz | Medigraph Compressed Database |
| .tmzip | Theme Manager Zip Format |
| .tn | LG Encoded JPG Image Format |
| .tn1 | Tiny Bitmap Image Format |
| .tn2 | Tiny Bitmap Image Format |
| .tn3 | Tiny Bitmap Image Format |
| .tn? | TiNY 2D Graphic |
| .tna | Topocad Net Adjustment |
| .tne | Manga Studio Tone Format |
| .tnef | Transport Neutral Encapsulation Format |
| .tnf | Transport Neutral Encapsulation Format |
| .tng | Namo WebCanvas Vector Graphic |
| .tnl | Thumbnail Image Format |
| .tnr | GPS Pathfinder ProXR/XRS Firmware |
| .tns | TI-Nspire Document |
| .tnsp | Texas Instruments TI-Nspire PublishView Document Format |
| .tnt | TurnTool 3D Model |
| .tnx | PCL Toolkit Text Extraction |
| .tny | TiNY Bitmap Image |
| .toast | Roxio Toast Disk Image Format |
| .tob | ZEMAX Object Data |
| .toc | Table Of Contents Format |
| .tocf | Eudora For Mac TOC |
| .tod | JVC Everio Video Capture Format |
| .toe | Touch Environment Project |
| .tof | Mr. Photo Temporary Thumbnail |
| .tofp | Toshiba Fingerprint Utility Settings Backup |
| .toh | Infinity Engine Game |
| .tok | Borland C++ 4.x External Tokens |
| .tokend | Smart Card Support Mac |
| .tol | AOL Tool Format |
| .tom | MediGraph Database |
| .tombRaider 3 | Tomb Raider 3 Save Game |
| .ton | FMS32 Protocol |
| .tool | Apple Mac OS X Terminal |
| .tools | DJGPP Tools |
| .top | Evernote Handwritten Notes And Sketches Format |
| .topc | TopicCrunch Stored Search Project |
| .topprj | TopSolid Project Format |
| .topx | E-sword Topic Note |
| .tor | Star Wars: The Old Republic Asset Format |
| .torchdownload | Torch Web Browser Partial Download |
| .torrent | BitTorrent Information Format |
| .tos | Atari ST TOS Archive |
| .tot | Bioware Infinity Game Engine Talk Table Override Text |
| .totalsbackup | Kedisoft Totals Database Backup Format |
| .totalsdb | Kedisoft Totals Database Format |
| .totalslayout | Totals Invoice Layout Format |
| .totalssyncdb | Kedisoft Totals Sync Database Format |
| .tox | Touch Component |
| .toy | Catz & Dogz Game |
| .tp | Beyond TV Transport Stream Format |
| .tp0 | Mascom PVR Video Format |
| .tp3 | Harvard Graphics DOS 3.0 Template Format |
| .tp4 | RollerCoaster Tycoon Track Design Screenshot Format |
| .tp7 | MODTRAN |
| .tpa | CorelDRAW Custom Graphic |
| .tpark | ThemePark Project Format |
| .tpb | GROMACS Portable Binary Run Input Format |
| .tpc | Topic Connection Placeholder |
| .tpd | JVC Cyberlink TOD Video Format |
| .tpe | Clarion Example |
| .tpf | Transit NXT Pack Translation Format |
| .tpg | TREAT Project |
| .tph | Turbo Pascal Help |
| .tpi | EDIUS Plugin Format |
| .tpic | TrueVision TARGA Image |
| .tpj | Nova Logic Game Terrain Project |
| .tpk | Tizen Application Package |
| .tpkey | TexturePacker License |
| .tpl | Generally A Template Format |
| .tpm | TextPad Macro Format |
| .tpo | TOPO! MapXchange Document |
| .tpp | Borland Pascal Protected Mode Units |
| .tpq | TOPO!Pro Map |
| .tpr | TMPEG Enc Video Conversion Project Format |
| .tps | Scam Torrent Format |
| .tpsdb | Print Shop Project |
| .tpt | ThumbsPlus Thumbnail Template |
| .tpu | Turbo Pascal Unit Format |
| .tpw | Borland Turbo Pascal Unit |
| .tpx | Photo Express Template Format |
| .tpz | Amazon Kindle Topaz E-book Format |
| .tqd | Torq Song Information |
| .tqf | Rational Test RealTime |
| .tql | Microsoft SQL Server Query Analyser Header |
| .tr | TomeRaider EBook Format |
| .tr0 | SPICE Transient Analysis Output |
| .tr1 | IBM Voice Type Languages Addword |
| .tr2 | Borland Turbo Debugger Session-state Settings |
| .tr3 | TomeRaider EBook Format |
| .tr4 | SPICE Transient Analysis Output |
| .tr5 | OnyxTree Professional Format |
| .tr6 | SPICE Transient Analysis Output |
| .tr7 | SPICE Transient Analysis Output |
| .tr8 | SPICE Transient Analysis Output |
| .tr9 | SPICE Transient Analysis Output |
| .tra | WinTrack Railroad Track Format |
| .trace | VMware ThinApp Trace Log Format |
| .tracwiki | Eclipse IDE WikiText |
| .trak | Native Instruments Traktor Content Pack Format |
| .transcriptstyle | Apple IChat Transcript Style |
| .trashes | Google Android Mobile Phone |
| .trashinfo | Trash Storage Metadata |
| .tray | Corel CONNECT Tray Format |
| .trb | Animation Master Turbulence Extension |
| .trc | Oracle SQL*Net Trace Debug Format |
| .trce | Corel Trace |
| .trd | TrID Definitions Package Format |
| .tre | EA SPORTS Game |
| .trec | Camtasia Studio Recorded Session |
| .tree | ES-Builder Tree |
| .trf | LFToolkit Transformation Rules |
| .trg | Symantec LiveUpdate |
| .tri | FaceGen Polygonal Model Format |
| .TriDefMovie | TriDef Movie |
| .TriDefPhoto | TriDef 3D Photo Transformer Depth Map |
| .trif | TRIF Tiled Raster Interchange Format Bitmap Format |
| .trk | Garmin GPS PCX5 Track Format |
| .trl | Topocad |
| .trm | Terminal Settings Format |
| .trn | Microsoft SQL Server Transaction Backup Format |
| .tro | IBM Voice Type Languages Vocable |
| .trp | MPEG-2 HD Video Format |
| .trr | GROMACS Full-precision Trajectory |
| .trs | Rosetta Stone Language Data Format |
| .trt | Team Sports Scheduling System Report Template |
| .tru | True Basic Source |
| .truck | Rigs Of Rods Truck Definition Format |
| .trv | Traverse PC Desktop Survey Data |
| .trx | Microsoft Visual Studio Test Results Format |
| .trx_dll | Windows Startup Format |
| .trz | Norton Antivirus Rapidrelease Definition Update |
| .ts | MPEG-TV Recorded Format |
| .ts0 | Tio32 Script |
| .ts1 | VirtualBus Texture Description Format |
| .ts2 | Time Stamp Project Information |
| .ts4 | Recorded Multimedia |
| .tsb | 3dMD Or 3Q Viewer 3D Image |
| .tsc | Microsoft Windows WinHelp Related Format |
| .tsd | NovaLogic Game Tile Surface Define |
| .tsf | ProWORX Nxt Symbol Format |
| .tsg | TSG Data |
| .tsi | Traktor Pro MIDI Map Format |
| .tsk | Pocket PC Skin |
| .tsm | Turbo Assembler For OS/2 Manual Format Format |
| .tsn | RatLab Toolkit |
| .tso | Tactical Situation Object XML |
| .tsp | Microsoft Windows Telephony Service Provider Format |
| .tsr | TSR Launcher |
| .tss | Team Sports Scheduling System Project Format |
| .tst | TestPoint Test Format |
| .tstream | SwarmPlayer Video Stream Control Format |
| .tsv | Tab Separated Values Format |
| .tsw | NI TestStand Workspace |
| .tsx | Team Sports Scheduling System XML Project |
| .tsz | Trillian Skin Format |
| .tt | Microsoft Visual Studio Text Template Format |
| .tt10 | Intuit Turbotax Tax 2010 Return Format |
| .tt11 | TurboTax Canada 2011 Tax Return Format |
| .tt12 | TurboTax 2012 Tax Return Format |
| .tt13 | TurboTax 2013 Tax Return |
| .tt2012state | TurboTax 2012 State Tax Form |
| .tt4 | TempTale |
| .tta | TTA Lossless Audio Codec Format |
| .ttarch | Telltale Games Game Data Format |
| .ttarch2 | The Walking Dead Season Two Game Data |
| .ttbk | Canadian TurboTax 2010 Backup Format |
| .ttbl | TTPLayer Play List |
| .ttbs | Microsoft PowerPoint For Mac Toolbar |
| .ttc | TrueType Font Collection |
| .ttd | Tinytag Data Log |
| .tte | Private Character Editor Format |
| .ttf | TrueType Font Format |
| .ttg | Command & Conquer Red Alert 3 |
| .tth | Vampire - Bloodlines Game |
| .tti | Beast Trojan |
| .ttk | Alchemy Catalyst Translation Toolkit Format |
| .ttkgp | TatukGIS Editor Project Format |
| .ttm | Tower Toppler Level Format |
| .ttn | Bentley InRoads Topologically Triangulated Network |
| .ttpl | TTPLayer Play List |
| .tts | ToolBook Translation System Format |
| .ttt | TestTrack Pro Database |
| .ttx | TRADOS TagEditor TRADOStag XML Format |
| .ttxt | MPEG-4 Timed Text Subtitles Format |
| .tty | Macromedia Dreamweaver |
| .ttz | Vampire The Masquerade |
| .tu | Turing Source Code Format |
| .tu? | Standard Mail Archive |
| .tub | Corel PaintShop Photo Pro Picture Tube Format |
| .tud | ThumbsPlus Graphics |
| .tui | NI LabWindows User Interface |
| .tun | Lego Racers Music Format |
| .tuneao | Marathon 2 Aleph One |
| .tur | Turing Program Source Code Format |
| .turboc3 | Borland Turbo C Makefile |
| .tut | Children Of The Nile Tutorial Format |
| .tuw | Microsoft Office |
| .tv | Corel Paradox Table View Settings |
| .tv1 | Corel WordPerfect Overflow |
| .tv2 | Corel WordPerfect Overflow |
| .tv3 | Corel WordPerfect Overflow |
| .tv4 | Corel WordPerfect Overflow |
| .tv5 | Corel WordPerfect Overflow |
| .tv6 | Corel WordPerfect Overflow |
| .tv7 | Corel WordPerfect Overflow |
| .tv8 | Corel WordPerfect Overflow |
| .tv9 | Corel WordPerfect Overflow |
| .tva | Truevision3D Animated Actor |
| .tvc | IBM Lotus 1-2-3 Table |
| .tvd | Apache Lucene Term Vector Documents |
| .tvex | Apple QuickTime MoviePlayer Extension |
| .tvf | DBASE Table View Settings |
| .tvg | Toon Boom Vector Graphics |
| .tvixie | TViXiE Effects |
| .tvj | TrueView Job Ticket |
| .tvl | TurboTax Format |
| .tvm | The Tube |
| .tvn | Yamaha Tyros 2 Voice |
| .tvod | Apple QuickTime Movie Or JPEG Picture |
| .tvp | TVP Animation Animation Data |
| .tvpi | TitanTV Television Listing Format |
| .tvr | Navicat For MySQL |
| .tvs | TeamViewer Session Format |
| .tvt | IBM Lenovo ThinkVantage Rescue And Recovery |
| .tvvi | TitanTV Television Listing Format |
| .tvx | Apache Lucene Term Vector Index |
| .twain | Adobe Acrobat TWAIN 1.8 Specification |
| .twb | Tableau Workbook Format |
| .twbx | Tableau Packaged Workbook Format |
| .twc | TTWin Configuration Format |
| .twd | MindMapper Brainstorm And Visual Map |
| .twdx | MindMapper Document |
| .twe | ThinkWave Educator Data |
| .twf | ArcView World Coordinates |
| .twg | CARE-S InfoWorks Trade Waste |
| .twi | SDDS Toolkit |
| .twig | Twig Source |
| .twiki | Eclipse IDE WikiText |
| .twk | TweakS |
| .twl | Naviguide Binary Route |
| .twm | TeamWORKS Module Launcher Format |
| .twp | Teamwork Planner Project |
| .tws | TextPad Workspace |
| .twt | Carmageddon 2 Carpocalyse Now Saved Game Format |
| .twv | VCM-ROM Linker Voice |
| .tww | Tagwrite Template |
| .twz | TheWord Compressed Module Format |
| .twzip | TheWord Compressed Module Format |
| .tx | Photoline 5 Help |
| .tx0 | Portable Radiation Package Data |
| .tx3g | MPEG-4 |
| .tx8 | 8-bit DOS ASCII Text |
| .tx? | LoseThos Text |
| .txa | Clarion Exported To Text Format Format |
| .txb | Descent / Descent 2 Encoded Briefing |
| .txc | Urban Chaos Game |
| .txd | Grand Theft Auto III Texture Dictionary |
| .txe | Enriched Text |
| .txf | Tax Exchange Format |
| .txh | Light Markup Language Text |
| .txi | KOTOR2 Game |
| .txl | Genesis3D Texture |
| .txm | CFPwinMan Document |
| .txn | MySpace IM Log Format |
| .txo | Panda3D Texture Object |
| .txp | Tweaking Toolbox XP Import/export Setting |
| .txr | CorelDraw Custom |
| .txt | Simple Text Format |
| .txt12 | IRI Scouting Database XML |
| .txtdt | TitleWriter DVD Text Data |
| .txtenx | Egis Encrypted TXT |
| .txtr | The Sims Texture |
| .txtrpt | CommScope Teletilt Control System Report |
| .txtz | EBook |
| .txu | CncCUT Program Text |
| .txv | RapidReader TextVision |
| .txw | Yamaha TX-16W Wave Format |
| .txx | Insight Segmentation And Registration Toolkit |
| .txz | XZ Compressed TAR Archive Format |
| .tx_ | Compressed Txt Format |
| .tyimport | Typinator Imported Set Format |
| .tym | Adobe PageMaker Time Stamp |
| .typeit4me | TypeIt4Me Clippings Format |
| .tyset | Typinator Set Format |
| .tz | TAR.Z Compressed File Archive |
| .tzb | TAR.Z.btoa Compressed File Archive (TAR - Compress - Btoa) |
| .tzd | Netscape Communicator |
| .tzi | Microsoft Windows CE Time Zone Information |
| .tzp | TrueZIP Ecnrypted JAR Java |
| .tzx | ZX Spectrum Tape Image Poke Format |
File extensions are not normally displayed to users. To change this, go to Control Panel, select Appearance and Personalization and Folder Options. Next, select the View and find the option "Hide extensions for known file types". The option should be deselected (cleared) and confirmed with OK.
