| H | Program header (C) |
| HA | Compressed archive (HA) |
| HAL | Hal add-on file (Lotus 1-2-3) |
| HAM | Driver file (Novell Netware) |
| HAM | Vector graphics saved file (Amiga) |
| HAP | Compressed archive (HA) |
| HBK | Handbook (MathCad) |
| HBK | Accounting data file (Humanic Software) |
| HCM | Configuration file (IBM HCM) |
| HCOM | Sound Tools file (HCOM) |
| HCR | Production configuration file (IBM HCD/HCM) |
| HDA | Document file (HotDocs) |
| HDF | National Center for Supercomputing Applications (NCSA) Geospatial Hierarchical Data format |
| HDF | Help file (Help development kit) |
| HDF | Hierarchical data file |
| HDL | Alternate download listing (ProComm Plus) |
| HDR | Database header (Pc-File+) |
| HDR | Datafile (Egret) |
| HDR | Message header text (ProComm Plus) |
| HDR | Message header text (1st Reader) |
| HDW | Vector graphics (Harvard Draw) |
| HDX | Help index (AutoCAD) |
| HDX | Help index (Zortech C++) |
| HED | Document (HighEdit) |
| HEL | Hellbender saved game (Microsoft) |
| HEX | Macintosh BinHex 2.0 file |
| HFI | HP font info (GEM) |
| HFX | Data file (US Robotics Rapid Comm Voice) |
| HGL | Drawing file (HP Graphics Language) |
| HH | Help system map (Generic) |
| HH | Header file (C++) |
| HHH | Precompiled header (Power C) |
| HHP | Help information for remote users (ProComm Plus) |
| HIT | Audio file (HitPlayer) |
| HLB | Help library (VAX) |
| HLP | Help file (Generic) |
| HLP | Windows Help file (DataCAD) |
| HMI | Human machine interfaces MIDI music file (Descent) |
| HMM | Alternate mail read option menu (ProComm Plus) |
| HMP | Human machine interfaces MIDI music file (Descent) |
| HMP | Database file (InfoMgr) |
| HNC | Program files (CNC) |
| HOG | Lucas Arts Dark Forces WAD file |
| HOG | Mission file (Descent 1-2) |
| HOG | Main data package file (Descent3) |
| HOT | Document file (HotSend) |
| HP8 | Ascii text Roman8 character set (NewWave Write) |
| HPC | Font language file (Hewlett-Packard) |
| HPF | HP LaserJet font (Adobe Pagemaker) |
| HPF | Partial download file (HotLine) |
| HPG | HPGL Plotter vector graphics (AutoCAD) |
| HPG | HPGL Plotter vector graphics (Harvard Graphics) |
| HPI | Font information (GEM) |
| HPJ | Help Project file (Visual Basic) |
| HPK | Compressed archive (HPACK) |
| HPM | Emm text (HP NewWave) |
| HPM | Alternative menu for privileged users (ProComm Plus) |
| HPP | Program header (C++) |
| HPP | Database file (InfoMgr) |
| HPP | Header file (Zortech C++) |
| HQX | BinHex (Macintosh 4.0) |
| HRF | Rastor graphic (Hitachi) |
| HRM | Alternate menu for limited users (ProComm Plus) |
| HS2 | Monochrome image (Postering) |
| HSC | FM synthesized music file (Used by many old games, e.g.:FINTRIS, ROL) |
| HSI | Graphic (Handmade Software, Inc.) |
| HST | History file (Generic) |
| HST | History file (ProComm Plus) |
| HT | HyperTerminal file |
| HTA | A HTML file that has been used to by viruses to update the system registry |
| HTM | A Web page (a file containing Hypertext Markup Language - HTML - markup) |
| HTML | A Web page (a file containing Hypertext Markup Language - HTML - markup) |
| HTT | Hypertext template (Microsoft) |
| HTX | Template (Extended HTML) |
| HWD | Presentation (Hollywood) |
| HWP | Korean word processor document format (HanGul) |
| HXM | HAM extension (Descent2) |
| HXM | Alternate protocal selection menu (ProComm Plus) |
| HXX | Header file (C++) |
| HY1 | Hyphenation algorythm (Ventura Publisher) |
| HY2 | Hyphenation algorythm (Ventura Publisher) |
| HYC | Datafile (Microsoft WordPerfect for Windows) |
| HYD | Hyphenation dictionary (Microsoft WordPerfect for Windows) |
| HYM | 3D Image binary file (Hymarc Scandata Scanner) |
| HYP | Compressed archive (HYPER) |
| H! | On-line Help (Flambeaux Help!) |
| H++ | Header file (C++) |
| H-- | Header file (Sphinx C--) |
2010 Liberty Boy
Le Havre