| .h | C/C++ Header Format |
| .h++ | Unusual C++ Header |
| .h-263 | H.263 Encoded Video |
| .h.263 | H.263 Encoded Video |
| .h0 | Magix Music Studio Format |
| .h00 | ARM EPROM HEX |
| .h01 | ARM EPROM HEX |
| .h04 | GE FIX32 Historical |
| .h08 | GE FIX32 Historical |
| .h10 | At Home Canada 2010 Tax Return Format |
| .h11 | At Home 2011 Tax Return Format |
| .h12 | At Home 2012 Tax Return Format |
| .h1c | Windows Vista File Related To Assistance Platform (AP) Help |
| .h1d | Microsoft Windows |
| .h1f | Microsoft Windows Assistance Platform Client Help |
| .h1h | Microsoft Windows Merged Hierarchy Help |
| .h1k | Keyword Index - Microsoft Windows Assistance Platform Client Help Related |
| .h1q | Microsoft Help Merged Query Index Format |
| .h1s | Microsoft Windows Assistance Platform Client Help Format |
| .h1t | Microsoft Windows Assistance Platform Client Help Related |
| .h1v | Task Metadata - Microsoft Windows Assistance Platform Client Help Related |
| .h1w | Microsoft Windows Keyword Index |
| .h260 | Video Recording |
| .h261 | H.261 Video Format |
| .h263 | H.263 Video Format |
| .h264 | H.264 Video Format |
| .h2drumkit | Hydrogen Drum Kit |
| .h2o | Battle Realms Game Data Format |
| .h2p | Zebra Preset |
| .h2song | Hydrogen Drum Notes |
| .h2w | H2testw |
| .h3b | POD HD300 Bundle |
| .h3c | Heroes Of Might And Magic 3 Campaign |
| .h3d | Altair HyperView 3D Model |
| .h3e | POD HD300 Preset |
| .h3m | Heroes Of Might And Magic 3 Map Format |
| .h4b | POD HD400 Bundle |
| .h4e | POD HD400 Preset |
| .h4m | Resident Evil Zero Game |
| .h4r | Heroes Of Might And Magic 4 Data Format |
| .h5 | Hierarchical Data Format Version 5 |
| .h5e | POD HD500 Preset |
| .h5s | POD HD500 Set |
| .h86 | CP/M |
| .ha | HA Compressed Archive |
| .hak | BioWare Aurora Engine |
| .hal | HansaWorld Enterprise HAL Code Format |
| .ham | Descent 2 Resource Format |
| .haml | HTML Abstraction Markup Language |
| .handlebars | Handlebars Template |
| .hang | Apple Mac OS X Terminal |
| .hap | HAP Compressed File Archive |
| .har | E-Sword Harmony Resource |
| .harddisk | Boxer For Mac Harddisk |
| .harx | E-sword Harmony |
| .has | Haskell Script Format |
| .hash | EnCase Forensic Drive Image Hash |
| .hat | Formula 1 Car Race 2001 Log Hat |
| .hathdl | Hentai@Home Download |
| .hav | Video Recorder Video |
| .haz | Microsoft Flight Texture |
| .hbc | HyperBac Compressed Archive Format |
| .hbc2 | HyperBac Compressed Archive |
| .hbe | HyperBac Compressed/encrypted Archive |
| .hbk | Mathcad Handbook Format |
| .hbm | Hibernate Script |
| .hbn | Java Hibernate |
| .hbr | HaxBall Replay |
| .hbx | BinHex Compressed File ASCII Archive |
| .hbz | StarMoney Macro |
| .hcb | HyperOS Compressed Backup |
| .hcc | HydroCAD Storage Chamber Definition Format |
| .hce | HydroCAD Hydrograph Data Format |
| .hcf | Compact Ham Library |
| .hcfg | HoDokK Configuration |
| .hcg | HClab Chart |
| .hci | HydroCAD IDF Data Format |
| .hcl | HotDocs Library Format |
| .hcom | Sound Tools HCOM Audio |
| .hcp | HydroCAD Project Format |
| .hcr | HydroCAD Stormwater Modeling System Rainfall Definition |
| .hcs | NHP ESubmission Builder Submission Package |
| .hct | Symantec LiveUpdate |
| .hcu | HydroCAD Hydrograph Units Definitions Format |
| .hcw | HTML Help Workshop Conversion Wizard Macro |
| .hcx | Harvard ChartXL Chart Format |
| .hd2 | Poser Hand Pose Format |
| .hda | HotDocs Document File Format |
| .hdb | HansaWorld Enterprise Database Format |
| .hdc | HD Tach Benchmark |
| .hdd | Parallels Workstation Virtual Hard Disk Format |
| .hde | NAUPA File Encryptor Encrypted |
| .hdf | Hierarchical Data Format |
| .hdf4 | HDF4 |
| .hdf5 | HDF5 |
| .hdi | Autodesk AutoCAD Heidi Device Interface |
| .hdk | HotDocs Registration Format |
| .hdl | Procomm Plus Alternate Download Format Listing Format |
| .hdm | HDML Handheld Device Markup Language Format |
| .hdml | Handheld Device Markup Language |
| .hdmov | Apple QuickTime HD Movie Format |
| .hdmp | Microsoft Windows Heap Dump Format |
| .hdp | HD Photo |
| .hdpmx | HotDocs Publisher Mapping XML Format |
| .hdr | High Dynamic Range Image Format |
| .hdrp | HDRtist Graphic Format |
| .hdru | Apollo HRDU Image Format |
| .hds | Windows Digital Right Management Format |
| .hdt | Photoshop HDR Toning Preset Format |
| .hdumx | HotDocs User Mapping XML Format |
| .hdv | High Definition Video Format |
| .hdx | Delphi MultiHelp Index Format |
| .hdz | Poser Compressed Hand Pose Format |
| .he4 | HDF4 |
| .hea | Fifa 2001 Data |
| .heartssave-ms | Hearts Saved Game Format |
| .heb | DEcomp 3D Scene Data |
| .hed | Hi-Eddi Image |
| .hef | HEAT Export |
| .help | Unix Help Format |
| .helpcfg | Adobe AIR Help Configuration |
| .helpindex | Mariner Software Narrator Index |
| .hep | Novell NetWare Help Librarian Data |
| .hes | TurboGrafx-16 Audio |
| .het | WinSQL HTML Export Template |
| .heu | Adobe Flash Player Cache Metadata |
| .hex | Hex Dump Format |
| .hf | HF Image Format |
| .hfa | Erdas Imagine Hierarchical |
| .hfb | Hell Fighter Battle |
| .hfc | H-JTAG Configuration |
| .hfd | HotDocs Form Document Format |
| .hfmx | HFM.NET Configuration |
| .hfo | Pinnacle Hollywood FX Object |
| .hfp | XnView Filter |
| .hfs | MacImage Macintosh HFS Disk Image Format |
| .hfss | Ansoft HFSS Project |
| .hft | HaftiX Cross-stitch Pattern |
| .hfv | Virtual Mac Hard Drive Format |
| .hfx | Harvard Graphics F/X |
| .hg | HP Graphics Language |
| .hg1 | Hellgate: London Saved Game |
| .hgd | IP Camera Video |
| .hgh | Star Wars: Tie Fighter High Score |
| .hgl | Hewlett-Packard Graphics Language Format |
| .hgp | HighGrow Plant |
| .hgs | Harvard Graphics Graphic |
| .hgt | Shuttle Radar Topography Mission Data SRTM Format |
| .hgz | ArcMap GIS |
| .hh | C++ Header Format |
| .hhc | HTML Help Table Of Contents Format |
| .hhh | Power C Precompiled Header Format |
| .hhk | Microsoft HTML Help Index Format |
| .hhl | Visual Basic |
| .hhp | Microsoft HTML Help Project |
| .hhpack | HTC Home Extension |
| .hhs | Microsoft HTML Help Workshop Sample |
| .hhsl | Hockey High Score List Format |
| .hht | Microsoft Help And Support Center HHT Format |
| .hi | High Scores Format |
| .hic | HicEst Script |
| .hid | Sony Ericsson Configuration Archive Format |
| .hid2 | KeepSafe Encrypted |
| .hif | Quicken Online Format |
| .hil | Deluxe Ski Jump 3 Hill |
| .him | ROSE Online Highmaps |
| .hin | HyperChem HIN Chemical Modeller Input |
| .hip | Houdini Project Format |
| .hipnc | Houdini Apprentice Format |
| .hips | Bitmap |
| .hir | Hires C64 Image Format |
| .his | FindinSite Database Definition Format |
| .hisawsave | Nancy Drew Saved Game |
| .hisf | DL_POLY History |
| .history | Eclipse IDE Local History |
| .hisu | DL_POLY History |
| .hit | The Sims Sound Format |
| .hiv | Windows NT Registry Hive |
| .hjt | TreePad Editor Format |
| .hkc | HTML-KIT Auto Complete Short Cut |
| .hkdb | Apple ITunes Database Format |
| .hke | Painkiller Overdose Game |
| .hkf | Microsoft.NET Framework |
| .hki | WinHKI Compressed Archive Format |
| .hki1 | WinHKI HKI1 Compressed Archive Format |
| .hki2 | WinHKI HKI2 Compressed Archive Format |
| .hki3 | WinHKI HKI3 Compressed Archive Format |
| .hkl | RMCProfile Range Of Values |
| .hkm | Havok Movie Format |
| .hks | HTML-KIT Plugin |
| .hkx | Skyrim Animation |
| .hl | HeuristicLab Storage Format |
| .hl$ | MS-DOS Compressed Help |
| .hl1 | Half-Life Saved Game |
| .hl6 | Horizontal.Log 6 |
| .hla | High Level Assembler Source |
| .hlb | VAX VMS Help Library Format |
| .hlc | ESO MIDAS Help Command |
| .hld | Structural Desktop Hold |
| .hlf | FAR Manager Help |
| .hlk | Warhammer 40k Dawn Of War 2 Animation |
| .hln | MicroStation Hidden Line |
| .hlog | VMware Workstation Log |
| .hlp | Help Format |
| .hlq | ESO MIDAS Help Qualifier |
| .hlsl | High Level Shader Language Source Code Format |
| .hlt | Watcher Database Trades List |
| .hlw | Win32/AMalum.EDHZ |
| .hlx | ATI Radeon Video Driver Format |
| .hlz | MultiEdit Packed Help |
| .hm | Windows Help Context IDs |
| .hm0 | MAGIX Audio Cleaning Lab Waveform |
| .hm2 | Help & Manual Help File Project |
| .hm3 | Help & Manual Help File Project |
| .hma | Sony MiniDisc Audio Format |
| .hmap | Microsoft SharePoint Server 2007 Temporary |
| .hmap.Dir | Microsoft SharePoint Server 2007 Temporary |
| .hmax | Custom 3ds Max Format |
| .hmd | SWAT Relative Humidity Input |
| .hme | Smartphone Theme Format |
| .hmf | HOOPS Metafile |
| .hmgd | Microsoft Grammar |
| .hmhd | Word Hyphenation Format |
| .hmi | HMI Audio Format |
| .hmk | Hallmark Card Studio Card Format |
| .hml | HostMonitor TestList Format |
| .hmmer | SAM HMMER Format |
| .hmmr | SAM HMMR |
| .hmp | Worms Height Map Format |
| .hms | HostMonitor Script Format |
| .hmsd | Microsoft Dictionary |
| .hmskin | Help & Manual Help File Skin |
| .hmt | HighMAT Format |
| .hmx | Help & Manual Help File Project |
| .hmxp | Help & Manual Help File Uncompressed XML Project |
| .hmxz | Help & Manual Help File Compressed XML Project |
| .hmy | Hemingway Content Management System Plugin |
| .hm~ | Help&Manual Help Project Backup |
| .hnc | NoteCenter Note |
| .hnd | HNSKY Deep Sky Database |
| .hnf | HNF Split & Merge Channels |
| .hnr | Teleatlas |
| .hob | Star Trek Birth Of The Federation Ship Graphic Data |
| .hod | Homeworld Object Data |
| .hog | Descent Hog Format |
| .hogg | Cryptic Studios Data |
| .hol | Microsoft Outlook Holiday Calendar Format |
| .honmod | Heroes Of Newerth Mod Format |
| .hop | Hippon Protected |
| .hot | The Sims Sound Format |
| .hotspot | Homeworld Cursor Informaiton |
| .hp | HP Graphics Language Plotter |
| .hp1 | HP Graphics Language Plotter |
| .hp2 | HP Graphics Language Plotter |
| .hp? | LoseThos C+ Header |
| .hpc | System Dynamic Library |
| .hpd | HotDocs PDF Document Format |
| .hpf | High Performance FORTRAN Format |
| .hpfs | OS/2 High Performance File System |
| .hpg | HP Graphics Language Plotter Format |
| .hpgl | Hewlett Packard Graphics Language Plot Format |
| .hpgl2 | Hewlett Packard Graphics Language 2 |
| .hpi | Hemera Photo Image Format |
| .hpj | Microsoft Win Help Project Format |
| .hpk | Haemimont Games Game Package Format |
| .hpl | Hewlett-Packard LaserJet Vector Image Format |
| .hplg | Apple ITunes Device Plugin |
| .hpm | Procomm Plus Alternate Main Menu |
| .hpo | HippoDraw Canvas Document |
| .hpp | C++ Header Format |
| .hpr | RoboHelp Settings |
| .hprj | Heroglyph Project |
| .hprof | Java Heap Dump |
| .hps | HPL2 Script |
| .hpt | HotDocs PDF Template Format |
| .hpx | MetaVR 3D Model |
| .hpz | Helpinator Project |
| .hqf | QuiltCAD Stitch |
| .hqr | Little Big Adventure HQR |
| .hqx | Macintosh BinHex Archive |
| .hr | TRS 80 Image File Format |
| .hr2 | Poser Hair Format |
| .hrc | Autodesk Softimage Model 3D |
| .hrd | MSC Patran Device-dependent Hardcopy |
| .hrf | Hitachi CADCore Raster Format |
| .hrl | Erlang Source Or Script Format |
| .hrm | Polar ProTrainer Pulse Rate Save |
| .hrs | Holder Reporting System |
| .hru | HRU Image Format |
| .hrx | Herolab EasyWin32 |
| .hrz | Poser Compressed Hair Format |
| .hs | Literate Haskell Source Code Or Script Format |
| .hs2 | HyperRESEARCH Postering Monochrome Image Format |
| .hsb | HALion Sampler Format |
| .hsc | Aspen HYSYS Simulation Format |
| .hse | Adobe Dreamweaver Snippet |
| .hsf | HOOPS Stream Format |
| .hsh | Windows Catalog Search Index Format |
| .hsi | Handmade Software Bitmap Image |
| .hsk | Nimbus 7 SAMS Data Format |
| .hsm | The Sims Sound |
| .hsp | HSC Composer Packed By Number Six |
| .hsql | HtmSQL Html |
| .hsr | RezeptAssist Import Or Export |
| .hss | Adobe Dreamweaver Snippet |
| .hst | Yahooo Messenger History Format |
| .hstx | Altair HyperStudy Package |
| .hsv | Diablo: Hellfire Singleplayer Character Data |
| .hsx | Health & Safety Xpert Project |
| .ht | HyperTerminal Session Format |
| .ht1 | Google Desktop Application Data |
| .ht4 | HTML Version 4 |
| .hta | HTML Program Format |
| .htaccess | Apache Access Configuration Format |
| .htb | Audacity Help Format |
| .htc | HTML Component Format |
| .htd | Adobe ExtendScript HTML |
| .htg | HackTheGame Mission Pack Format |
| .htgroup | Apache Server User Group |
| .hti | Microsoft Windows WinHelp Related |
| .htk | Hidden Markov Model Toolkit Speech Recognition |
| .htm | HTML Hypertext Markup Language Web Page Format |
| .html | HTML Hypertext Markup Language Web Page Format |
| .html0 | Book Designer E-book Format |
| .html5 | HTML5 Hypertext Markup Language Revision 5 Source |
| .htmlenx | Egis Encrypted HTML |
| .htmls | HyperText Markup Language Document With Server-side Include |
| .htmlz | Zipped HTML Format |
| .htms | PHP HTML Document |
| .htn | Micrografx Picture Publisher 8 Print Style |
| .htp | Autodesk Slope Template Definition |
| .htpasswd | Apache Access Configuration Format |
| .htpl | IBM Rational Application Developer WebContent Theme |
| .htr | Microsoft Windows NT Password Services Script |
| .htri | HTRI Xchanger Suite Data Input |
| .htt | Microsoft HyperText Template Format |
| .htw | Windows |
| .htx | Microsoft FrontPage Database Results |
| .htxt | Hanvon WISEreader E-book Format |
| .htz4 | HyperMaker Publication Format |
| .htz5 | HyperMaker Document Format |
| .hud | SmartWare Dictionary |
| .huh | HydroCAD Unit Hydrograph Definitions Format |
| .hul | Re-Volt Collision Data |
| .hull | Half-Life Map Collision Hull |
| .hun | Personal Paint Hungarian Language User Interface |
| .hup | Haihaisoft DRM-X Protected Video |
| .hus | Husqvarna Embroidery Format |
| .huv | Husqvarna Viking Designer Graphic |
| .hv | Microsoft Windows Mobile Hive |
| .hva | Command And Conquer Tiberian Sun Voxel Animation Control |
| .hvc | ASCII Format |
| .hvd | HoverDesk Theme |
| .HVIF | Haiku Vector Icon Format |
| .hvl | Commodore Amiga HivelyTracker Audio Module |
| .hvpl | Apple ITunes Visual Plugin Format |
| .hwd | Hedgewars Game Replay Format |
| .hwl | Corel WordPerfect Shared Writing Tools 9.0 |
| .hwmap | Hedgewars Drawn Map Format |
| .hwof | Microsoft Office For Mac Help |
| .hwp | Hangul Document Format |
| .hws | Hedgewars Saved Game Format |
| .hwt | Huawei Ascend P6 Emotion UI Theme |
| .hwx | RSNetWorx Registration |
| .hx | Haxe Source Code |
| .hxa | Microsoft Help Attribute Definition Format |
| .hxc | Microsoft Visual Studio Collection Definition Format |
| .hxd | Microsoft Help Validator |
| .hxe | Microsoft Help 2 Sample Definition Format |
| .hxf | Microsoft Help Include |
| .hxh | Microsoft Help Merged Hierarchy |
| .hxi | Microsoft Help Compiled Storage |
| .hxk | Microsoft Help 2 Keyword Index Format |
| .hxl | Microsoft Help Registered Namespace List |
| .hxm | Descent 2 Resource Modification Format |
| .hxml | HaXe Make |
| .hxn | Hexagon Model Format |
| .hxp | HaXe Project |
| .hxproj | FlashDevelop Flash Project |
| .hxr | Microsoft Help Data |
| .hxs | Microsoft Help Compiled Storage Format |
| .hxt | Help Table Of Contents Format |
| .hxv | Microsoft Help Virtual Topic Definition |
| .hxw | Microsoft Help Attribute Definition |
| .hxx | C++ Header Format |
| .hy1 | Ventura Publisher Hyphenation Algorithm |
| .hy2 | Ventura Publisher Hyphenation Algorithms |
| .hyc | Corel WordPerfect Data |
| .hyd | Corel WordPerfect Hyphenation Dictionary |
| .hydra | Hydra Image Filter Program Format |
| .hym | Hymarc Scandata Scanner 3D Image Binary |
| .hyp | Adobe Acrobat Dictionary Format |
| .hype | Hype Web Project Format |
| .hyq | CARE-S InfoWorks Hydrograph |
| .hyv | HY-TEK Sports Team Manager Meet Event Format |
| .hz | Chinese (Hanzi) Text |
| .hzd | SeisWorks |
| .h_ | Microsoft Winhelp Compressed |
| .h__ | C++ Header |
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.
