List of File Types/ File extensions Part 1

This list of file types sets out to answer the common question "What is a file of type .x?" or "What is that file extension for?"
A file type is denoted by those letters that follow the last dot in a file name. These letters denote the type of file, and are also commonly known as a file extension. On Windows PCs the file extension may be hidden by Windows, but is still part of the file name.
This list of file types contains a list of file extensions together with a brief description of the type of file that the extension is associated with.
Computer 'A' file extensions
1. .a - UNIX static library file / ADA source code file.
2. .a3w- Macro Media Authorware 3.5 file.
3. .abk- Auroback file used with corel Draw 6 and above.
4. .abr- Brush file for Adobe Photoshop 
5. .ac - ACwin project file/GNU Autoconf configuration script/AC3D geometry file/Acceleration record file.
6. .acc - GEM desk accessories file.
7. .accdb - Microsoft Access 2007 database file.
8. .ace - ACE Archiver compression file./ WinAce compressed file.
9. .acr - ACR file format for medical images.
10. .act - Action diagram (FoxPro) / Action File (Animation Master)./ Adobe Photoshop Color table file.
11. .acv - Adobe Photoshop compensation curve file.
12. .ad -  After Dark file or a Microsoft "Access Point" file.
13. .ade - Microsoft Access project extension.
14. .adf - Adapter description files.
15. .adp - Microsoft Access project file / Dynamic web page.
16. .adr - After Dark randomizer or Opera browser bookmark backup.
17. .adm - Addict Dictionary file / Group Policy Administrative Template file./ After Dark screen saver module.
18. .afw - Bullion firmware file.
19. .agd - Agile Advantage file / AgileGraph data file.
20. .ai - PostScript viewer / Acrobat Illustrator vector graphics file / AIwin project file.
21. .aid - MapXtreme generated file.
22. .aif - Audio Interchange File./ Auto Interchange File Format (AIFF) Audio file.
23. .aifc - Compressed audio file.
24. .aiff - Audio Interchange File.
25. .ald - Axapta Label Data file.
26. .alg - ESRI Mapper File / HDLmaker file.
27. .als - Part of the Delphi help file system.
28. .amm - Adaptive Message Macro file.
29. .amp - Arbitrary Map file.
30. .amv - Audio-Video media file.
31. .ani - Animated cursor file./ Windows animated mouse cursor file.
32. .aod - Microsoft Dynamics AX Application Object Data file.
33. .apn - ApneaGraph data file / Wallpaper graphics file / REC Navigation application.
34. .app - VoxPro file / GEM file.
35. .application - ClickOnce application manifest file.
36. .aps - Binary file.
37. .arc - Compressed file.
38. .arj - Compressed file.
39. .as - Flash ActionScript file./ Short for AppleSingle, .AS is a compressed file extracted and used with various compression utilities.
40. .asax - ASP.NET application file.
41. .asc - ASCII text file.
42. .ascx - Visual Studio custom user control source file.
43. .asf - Media player audio-visual file./ Sort for Advanced Streaming Format, file developed by Microsoft. The .ASF file is generally a movie player and can be open with software such as Windows Media Player.
44. .ashx - ASP.NET HTTP handler file.
45. .asm - Assembler file / Solid Edge assembly file / Pro ENGINEER assembly file.
46. .asmx - SP.NET web services source file.
47. .asp - Active Server page./ Microsoft FrontPage Active Server Pages. To open these files Use your Internet browser.
48.  .aspx - ASP.NET file.
49. .aspx.cs - Visual C# source file.
50. .aspx.resx .Net resource file.
51. .aspx.vb - VB.Net source file.
52. .atf - Adobe Transfer Functions file / Axon Text File.
53. .att - Email attachment.
54. .ato - Compaq Just Burn File.
55. .atx - Texture plug-in (Animation Master)
56. .aty - 3D Topicscape association type file.
57. .au - µ-law sound file./ Sun and NeXT audio file
58. .aux - Auxiliary target file / Erdas Hierarchical File / LaTeX auxiliary reference file / ChiWriter auxiliary dictionary.
59. .av2 - Avatar2 model file (Animation Master)
60. .ava - Avatar model file (Animation Master)
61. .avi - Audio video file.
62. .awk - AWK script file.
63. .axd - ASP.NET internal HTTP handler file / Actrix technical 2000 file.
64. .axe - AutoRoute map export file.
65. .axr - ARCHPR project status file.
66. .axx - AxCrypt encrypted file.




Computer 'B' file extensions
1. .b3d - BodyPaint 3D file.
2. .b64 - Short for BASE64, .B64 is a compressed file extracted and used with various compression utilities.
3. .bad - Generic bad (corrupt) file / Non-delivered email.
4. .bak - Generic backup file./ Backup file used for important windows files usually used with the System.ini and the Win.ini.
5. .bas - BASIC source code file./ QBasic program and or Visual Basic Module.
6. .bat - MS-DOS batch file./ Batch file that can perform tasks for you in dos, like a macro.
7. .bbc - BBC BASIC for Windows program or data file.
8. .bbt - BTwin database file / bbTracker GPS track file / Basket Ball Team file.
9. .bc - BCwin project file / BitComet intermediary download file / Big Crunch compressed archive / Byte Code (LLVM) file.
10. .bcd - Board/Chip description file.
11. .bck - VMS backup file.
12. .bdb - Back of Works database file.
13. .bdp - Bad mail pointer file / Combat Flight Simulator 3 file.
14. .bdr - Bad mail report file / Microsoft Publisher Border file.
15. .bfc - Windows Briefcase file./ Microsoft Windows 95 / Windows 98 Briefcase file.
16. .bg – Backgammon game file.
17. .bil - Spot raster image file.
18. .bin - Generic binary / MacBinary encoded file / CD image./ Binary file used with various different programs./Translation tables for code pages other than the standard 437.
19. .bk - Adobe FrameMaker book file.
20. .bk2/3/4/5/6/7/8/9 - Corel Word Perfect for Windows Backup file.
21. .bkf - Windows backup file.
22. .bkp - backup file
23. .bks - Backup selection file.
24. .blk - Descent Mission Builder block file.
25. .bmc - Bitmap Cache file / Embroidery image file.
26. .bmp - Bit-map image file.
27. .bnk - Decent 2 FM sound instrument definition file./ Sim City Backup
28. .bpg - Borland Delphi project group file.
29. .bpl - Borland package library.
30. .bps - Microsoft Works Word Processor File
31. .bpt - Corel  Draw Bitmap master file.
32. .brd - Layout file for EAGLE EDA system / BizInt Smart Charts file.
33. .brk - Brooktrout Fax file.
34. .brn - BrainStorm model file.
35. .brw - ProMash session file.
36. .bsc - Browse information file.
37. .bt - BTwin project file / EVwin project file / ILwin project file.
38. .btk - TeKton database file.
39. .btm - Batch to memory file.
40. .btoa - Compressed file extracted and used with various compression utilities.
41. .bu - Pegasus mail temporary file.
42. .bud - Backup disk for Quicken.
43. .bup - Backup of a .ifo file.
44. .bv1/2/3/4/5/6/7/8/9 - Corel Word Perfect for Windows Backup file.
45. .bva - Biovision action file.
46. .bvh - Biovision hierarchical motion file.
47. .bvp - BlueVoda Publication file.
48. .bwp - Battery watch pro file. 
49. .bz - Compressed file extracted and used with bzip and bunzip various compression utilities.
50. .bz2 - Bzip2 compressed file./ Compressed file extracted and used with bzip2 and bunzip and various other compression utilities

Computer 'C' file extensions
1. .c - 'C' programming language source code.
2. .c4d - Clonk object definition file.
3. .c4f - Clonk scenario folder file.
4. .c4p - Clonk player file.
5. .c4m - Clonk material file.
6. .c4i - Clonk object info file.
7. .c4s - Clonk scenario file.
8. .c4q - Clonk queue file.
9. .c4v - Clonk video file.
10. .cab - Cabinet compressed file./ Cabinet file used in Windows 95 and Windows 98 that contains all the windows files and drivers. Information about how to extract a .
11. .cal - Windows Calendar, Supercalculator4 file or Supercal spreadsheet.
12. .cam - Camera file (Animation Master)./ Casio digital camera file.
13. .cas - Netica comma separated value text file of cases.
14. .cat - Security catalogue file.
15. .cbl - Cobol source file.
16. .cbt - Computer Based Training files.
17. .cc - C++ source file.
18. .ccd - CloneCD control file.
19. .cct - Adobe Director protected cast resource file.
20. .cd - Class diagram file / CD-i OptiImage CD image file / cdTree CD catalogue file.
21. .cd4 - Dymo DiscPainter file.
22. .cda - Compact disk audio track.
23. .cdd - Claris Draw graphics file / CVI symbol table / CADEX drawing / ConceptDraw document / UML file.
24. .cdl - SignLab vector graphics file / Common Data Language file / CAD Advanced Design Language file.
25. .cdr - CorelDRAW drawing / Raw Audio-CD.
26. .cdt - Corel Draw template file.
27. .cdx - Visual FoxPro compound index.
28. .cer - Certificate file.
29. .cf - CFwin project file / Sendmail configuration file / Piranha configuration file / Zimbra configuration file.
30. .cfb - Comptons Multimedia file
31. .cfm - Cold Fusion mark-up file
32. .cfml - Cold Fusion mark-up language file.
33. .cfg - Delphi configuration file / Outlook configuration file / Netgear router configuration backup file./ Configuration file
34. .cfl - Corel flowchart file
35. .cfm - Corel FontMaster file / Cold Fusion Template file / Visual dBASE windows customer   form
36. .cgf - CargoMap file.
37. .cgi - CGI web based program or script.
38. .chk - Scandisk file that is used to backup information that scandisk has found to be bad, found in C root. Because the information within these files are corrupted or reported as bad by Scandisk it is perfectly fine to delete these files, providing you are currently not missing any information. Additional information about scandisk can be found on our scandisk page
39. .cgm - CAD file.
40. .che - CHwinEHE project file / Chemical model file.
41. .chi - Help file index / ChiWriter document.
42. .chm - Compiled HTML help file.
43. .chml - Chameleon encrypted file.
44. .cho - Choreography file (Animation Master)
45. .chr - Charset file / Constraint Handling Rules file.
46. .chunk001 - First part of a File Splitter split file.
47. .chunk002 - Second part of a File Splitter split file.
48. .chunk003 - Third part of a File Splitter split file.
49. .cif - Easy CD Creator CD image file.
50. .cl - Common LISP source file / CLwin project file / Control Language file. /Generic LISP source code.
51. .cl3/4 - Easy CD Creator layout file.
52. .cla - Java Class file.
53. .class - Compiled Java class file.
54. .clg - Disk catalog database
55. .clk - Corel R.A.V.E. animation file.
56. .cll - Crick software clicker file
57. .clo - Cloe image
58. .clp - Windows clipboard file. / Quattro Pro clip art / Clipper 5 compiler script
59. .clr - WinEdit Colorization word list / 1st reader binary color screen image / PhotStyler color definition.
60. .cls - Latex class file / VB6 class file / GSEA Phenotype data format file./ Visual Basic Class module /  C++ Class definition
61. .clw - Class Wizard file / Clarion module file.
62. .cmd - Windows-DOS command script file.
63. .cmf - Corel Metafile.
64. .cml - PADGen company information file / Chemical Markup Language file.
65. .cmv - Corel Movie file.
66. .cn - CNwin account file / MIwin account file / ICM distance restraints file.
67. .cne - Configuration file that builds .COM files.
68. .cnf - Configuration file
69. .cnt - Contents file for a windows help file./ Help file (.hlp) Contents (and other file contents)
70. .cnv - ACD Systems Canvas 6,7, and 8 file.
71. .cnx - Pegasus mail temporary file.
72. .cob - COBOL source code file.
73. .cod - FORTRAN Compiler program code
74. .com - Executable command file./ File that can be executed.
75. .conf - Configuration file.
76. .config - NUnit Configuration file.
77. .coo - Coordinates file.
78. .cos2 - Pinnacle Studio file.
79. .cpe - Fax cover page file
80. .cpl - Control panel item file./ Windows 95 / Windows 98 / Windows NT Control Panel icons./ Compact Pro compressed file extracted and used with various compression utilities./CorelDraw Photopaint file.
81. .cpp - C++ language source file.
82. .cpt - Compact Pro file.
83. .cr2 - Canon RAW format file.
84. .cr5 - Survey Pro coordinates file.
85. .crd - Windows Card file.
86. .crt - Security Certificate file.
87. .crw - Canon RAW format file.
88. .cs - Visual C# source file.
89. .csp -Crystal Server Page / Caché Server Page.
90. .csproj - C# project file.
91. .css - Cascading style sheet file.
92. .cst - Adobe Director protected cast resource file / DesignWorks schema file / LogicWorks schema file.
93. .csv - 1. Comma-Separated Variable file. Used primary with databases and spreadsheets (Microsoft Excel / Openoffice Calc).
                2. Image file used with CopuShow.ct - CTwin project file / Nucleic acid sequence and base pairing information file / Cheat table file.
94. .ctl - Visual Basic Control source code file.
95. .ctt - Messenger contacts file.
96. .ctx - Visual Basic Control file / Ciphertext (encrypted text) file / Creativyst Table Exchange Format file / CyberTracker eXport file / Text file / Terminal Server .ini file backup.
97. .cue - Cue sheet file./ Description of a CD image file. Often used with .BIN file.
98. .cur - Microsoft Windows cursor file.
99. Cv5 - ACD Systems Canvas 5 file.
100. .cvs - CANVAS file./ ACD Systems Canvas drawing file.
101. .cvi - ACD Systems Image format file.
102. .cvx - CANVAS file./ ACD Systems Canvas 9 file.
103. .cwf - ClarisWorks file / COM-Watch File.
104. .cxt - Macromedia Director protected cast resource file.
105. .cxx - C++ language source file.

Computer 'D' file extensions
1. .d -  A D programming language source file.
2. .da - DAwin project file.
3. .daa - Direct-Access-Archive CD/DVD image file./ Short for Disk Access Archive, file used to store a disk image. Used with PoserISO.
4. .daf - Data file for Digital Anchor.
5. .dat - Generic data file / Mapinfo data file / c-tree plus database./ Data file, generally associated or extra data for a program to use.
6. .db - Generic database file / Borland Paradox database file / Thumbnail cache./ Paradox database file / Progress database file.
7. .db2 - dBase II file.
8. .dbc - Visual FoxPro database file./ Microsoft Visiual Foxpro database container.
9. .dbf - dBASE III database file / dBASE IV database file / dBASE 5 database file / FoxPro database file / ArcView dBASE file.
10. .dbg - MS-Dev debug file.
11. .dbi - Delphi Database Explorer file.
12. .dbk - dBase databse backup / Orcad schematic capture backup file.
13. .dbm - Cold Fusion template.
14. .dbo - dBase IV compiled program file.
15. .dbq - Paradox memo.
16. .dbt - dBase database text file.
17. .dbv - Flexfile memo field file.
18. .dbw - DataBoss database file.
19. .dbx - FoxPro table file / Outlook Express file./ Database file / DataBeam Image / MS Visual Foxpro Table.
20. .dcf - Copy protected media file container.
21. .dci - Delphi code template file.
22. .dcm - Dicom file format for medical images.
23. .dcp - Delphi component package.
24. .dcr - Delphi component resource file / Shockwave file/ Digital camera RAW file format
25. .dct - Delphi file / FoxPro file / Aurora dictionary.
26. .dcu - Delphi compiled unit.
27. .dcx - FoxPro database index./ Multipage PCX file.
28. .dd - DDwin project file / Mac Disk Doubler compressed archive file.
29. .ddf - Diamond Directive File.
30. .ddi - DiskDupe image file.
31. .ddp - Delphi diagram portfolio file.
32. .dds - Direct Draw Surface file.
33. .deb - Package file./ Debian Package file. See Dpkg definition.
34. .debuglog - MyDefrag log file.
35. .def - Windows library definition file.
36. .dem - Delphi file / Descent 1/2 demo file.
37. .dep - Dependency file.
38. .deploy - Deployable .NET file / DeployMaster file.
39. .der - Security Certificate file
40. .det - Descent Manager file.
41. .dev - Device Driver
42. .dfm - Delphi form file.
43. .dfn - Delphi support file for integrated translation environment.
44. .dft - Solid Edge drafting file.
45. .dib - Windows bitmap file.
46. .dif - Document Interchange Format; VisiCalc
47. .dg - Auto-trol vector graphics drawing file.
48. .dgn - MicroStation binary design file.
49. .dir - Shockwave file.
50. .djvu - DjVu File.
51. .dlg - Windows dialog resource file.
52. .dll - Dynamic Linked Library.
53. .dlm - (Microsoft) DownLoad Manager file / Akamai Download Manager file / 3ds Max file.
54. .dmd - Visual dBASE data module
55. .dmf - Delusion/XTracker Digital Music File
56. .dmg - Macintosh Disk Image.
57. .dmo - Demo file
58. .dmp - (Windows) Dump file.
59. .dms - Compressed archive file
60. .dmt - Delphi menu template file.
61. .dne - Netica Bayesian network text file (opens with netica.exe).
62. .dng - Digital camera RAW file format.
63. .do - ModelSim file / Stata command file.
64. .doc - Word document / Word Perfect document.
65. .docx - Microsoft Word (XML) document./ New Microsoft Word open standard introduced with Microsoft Word 2007.
66. .dos - Text file and DOS Specification Info
67. .dot - Microsoft Word template.
68. .dotm - Microsoft Word 2007 template supporting macros.
69. .dotx - Microsoft Word 2007 template.
70. .dpk - Delphi package.
71. .dpl - Delphi 3 package library.
72. .dps - DataPower script file.
73. .dr - DRwin project file / Digital Rights file / Disaster Recovery file.
74. .dro - Delphi object repository file.
75. .dpr - Delphi project file.
76. .drv - Driver file./ Device driver files that attach the hardware to Windows. The different drivers are system, keyboard, pointing devices, sound, printer/ plotter, network, communications adapter.
77. .drw - Brother word-processor file / Freelance file / Micrografx file / Autocad drawing / LinkWinds drawing.
78. .DS_Store - Mac OS X file describing the appearance of a folder.
79. .dsk - Delphi desktop file.
80. .dsm - Delphi symbol module / Visual Studio macro file.
81. .dsn - Tiny CAD file / ODBC File DSN.
82. .dst - Delphi desktop settings file.
83. .dt - Macintosh Data File Fork
84. .dta - Data file
85. .dtd - SGML Document definition file
86. .dtf - Q&A database
87. .dti - Delphi 5 diagram portfolio file.
88. .dtm - DigiRekker module
89. .dtp - Timeworks publisher text file/ SecurDesk! Desktop / Pressworks Template file.
90. .dun - Dial-up networking configuration file.
91. .dvf - Digital Voice File / Digital View Cam file.
92. .dvr-ms - Digital Video Recorder file.
93. .dwf - AutoCAD drawing.
94. .dwfx - AutoCAD drawing file.
95. .dwg - AutoCAD binary drawing.
96. .dwt - AutoCAD binary drawing template / Dreamweaver page template file / Expression Web Dynamic Web Template file.
97. .dx - Document Imaging file / Digital data exchange file
98. .dxb - AutoCAD binary drawing exchange format.
99. .dxf - AutoCAD drawing exchange format file.
100. .dxr - Macromedia Director Protected movie file.
101. .dyn - Lotus 1-2-3 file.
102. .dwf - Short for Design Web Format, DWF is an Autodesk file used to store formatted text on the Internet.
103. .dwg - AutoCad (CAD) Drawing Database

Computer 'E' file extensions
1. .e00 - ArcInfo export file.
2. .eb - EBwin project file.
3. .ecf - Extension Configuration file / Sage CRM component file / Efficient Calendar data file.
4. .ect - Exception Console Template file.
5. .ecw - Enhanced Compressed Wavelet.
6. .edb - Extensible Storage Engine database page file / Exchange database file / Windows update data store file / XEphem database file / Windows Search index database file.
7. .eeb - Button bar for Equation Editor in Word Perfect for Windows.
8. .eef - Digital camera RAW file format.
9. .eft - CHIWRITER high resolution screen characters.
10. .ega - EGA screen characters for Ventura Publisher.
11. .elg - Event List text file used with Prosa.
12. .elx - Elixir Form Design Suite file.
13. .emf - Enhanced Windows Metafile.
14. .eml - Microsoft Outlook e-mail file.
15. .ems - Enhanced Menu System configuration file for PC Tools.
16. .emu - IRMA Workstation for Windows emulation.
17. .enc - ADW Knowledge Ware Encyclopedia.
18. .end - CorelDraw arrow-head definition.
19. .epf - EAGLE Preferences file / Encapsulated PostScript file / Entrust profile file.
20. .eng - Sprint dictionary file engine.
21. .env - Word Perfect for Windows environment file.
22. .epg - Exported PaGe file used with DynaVox .
23. .eps - Encapsulated postscript file, with embedded TIFF preview images.
24. .eps2 - Adobe PostScript Level II.
25. .eqn - Word Perfect for Windows Equation file.
26. .erd - Entity Relation Diagram graphic file.
27. .erm - Entity Relation Diagram model file.
28. .err - FoxPro compilation error file./ Error log file.
29. .es - Sage CRM component script file.
30. .esh - Extended Shell Batch file.
31. .esl - FoxPro support library file.
32. .evt - Event log file./ Event file scheduler file for PC Tools.
33. .ex3 - Device driver for Harvard graphics 3.0.
34. .exc - QEMM exclude file from optimization file or Rexx program file.
35. .exd - Control information cache for Microsoft office document files.
36. .exe - Executable file / Self extracting archive/ Icon library file.
37. .exp - LIB export file / SonicWall exported configuration file.
38. .ext - Extension file for Norton Commander.
39. .ezs - EZ-R Stats batch script file.

Computer 'F' file extensions
1. .fas - Fast load lisp file.
2. .fcc - FreeProxy cache control file.
3. .fcd - Virtual CD-ROM file / FreeProxy cache data file / Flowcode file.
4. .fcg - FastCGI script.
5. .fcp - FLAMES Checkpoint Restart file (Ternion Corporation)
6. .fd - MO5 disk image file.
7. .fdf - Adobe Acrobat Forms Document.
8. .fdp - FlashDevelop project file / MapSonic memory card format map file / FileDisk Protector file.
9. .fes - 3D Topicscape fileless occurrence file.
10. .ff - AGFA CompuGraphics outline font description.
11. .ffa - Fast Find file.
12. .fff - GUS PnP bank / defFax fax document.
13. .ffl - Fast Find file/ PrintMaster Gold form file.
14. .ffo - Fast find file.
15. .fft - DCA/FFT final form text.
16. .ffx - Fast find file.
17. .fh - Simplex database form file.
18. .fits - Flexible Image Transport System file.
19. .fky - FoxPro macro file.
20. .fla - Flash movie file.
21. .flk - Flock plugin (Animation Master)
22. .fll - FoxPro dynamic link library.
23. .flv - Flash Video File.
24. .fm - Adobe FrameMaker document file.
25. .fmt - FoxPro format file / Tharo Systems label file.
26. .fnd - Microsoft Windows search file. Works in Microsoft Window XP and later.
27. .fnt - Font file / Descent font file.
28. .fol - First Choice Database file.
29. .fon - System font file/ Font files to support display and output devices.
30. .for - Fortran source code file.
31. .force - Microsoft Visual Studio file.
32. .fp - FinePrint AutoSave file / FoxPro configuration file / CRiSP Fishery Policy file.
33. .fp5 - Filemaker Pro database file.
34. .fp7 - FileMaker Pro database file.
35. .fpb - FLAMES Playback file (Ternion Corporation).
36. .fpr - FLAMES Prototype file (Ternion Corporation).
37. .fpt - Foxpro table memo.
38. .fpx - FlashPix image file.
39. .fqy - FLAMES FLARE Command file (Ternion Corporation).
40. .fr3 - dBase IV renamed dBase III+ form.
41. .frc - FLAMES RECORD Output file; FLARE Input file (Ternion Corporation).
42. .frf - FontMonger Font.
43. .frg - dBase IV uncompiled report.
44. .frk - Compressed zip file used with Apple Macintosh computers.
45. .frm - Visual Basic source code / MySql table definition file.
46. .fro - dBase IV compiled report / FormFlow file.
47. .frp - PerForm Pro Plus Form.
48. .frs - WordPerfect graphics driver.
49. .frt - FoxPro report.
50. .frx - FoxPro report / Visual Basic form binary file.
51. .frz - FormFlow file.
52. .fsc – FLAMES Scenario file (Ternion Corporation).
53. .fsh – EA Sports file/ Firestarter projects file. Used by Habanero Firestarter.
54. .fts - Help index file.
55. .ftw - Family Tree Maker export file
56. .fxp - FoxPro compiled program.

Computer 'G' file extensions
1. .gbi - Delphi database explorer file / gBurner Image file.
2. .gbm - MapServer bitmap store file.
3. .gdb - MapServer database file / Interbase file.
4. .gds - MapServer dataset file.
5. .ged - GEDCOM file.
6. .gem - GEM metafile.
7. .gen - ARC Digitized graphics file / Compressed Digitized Graphics file
8. .gho - Ghost Backup File.
9. .gid - Windows (help) global index.
10. .gi - Global Image file.
11. .gif - GIF image file./ CompuServe Graphics Interchange Format
12. .gix - MapServer sheet index file.
13. .gjm - Compressed audio file (mono).
14. .gjs - Compressed audio file (stereo).
15. .gmt - Zmodeler2 filter file.
16. .gpd - Generic Printer Driver file / CRISP output file / Gameplay data file / Grid Parameter Definition file / Visual Epr input file.
17. .gr2 - 286 grabbers that specify which font to use with DOS and Windows
18. .gr3 - 386 grabbers that specify which font to use with DOS and Windows
19. .gra - Gradient plugin (Animation Master)./ Microsoft Flight simulator graphics file.
20. .grb - Microsoft MS-DOS shell monitor.
21. .grc - Vertical Mapper Classified Grid file.
22. .grd - Vertical Mapper Continuous grid file / RockWorks XYG data file.
23. .grf - Micrografx draw/graph files.
24. .grp - Program Manager Group file.
25. .gsf - MapServer sheet file.
26. .gvp - Google Video Player File.
27. .gz - Unix compressed file./ Compressed file extracted and used with gzip and gunzip various compression utilities.
28. .gzip - Compressed file.

Computer 'H' file extensions
1. .h - Header file.
2. .hal - HAL code source file.
3. .ham - Descent 2 game data attribute file.
4. .hbk - Mathcad handbook file.
5. .hcsp - HTML page generated from Stellent CMS.
6. .hdb - Hansa DataBase file.
7. .hdl - Procomm Plus alternate download file listing.
8. .hdmp - Windows Heap Dump File.
9. .hdr - Procomm Plus message header or High Dynamic Range file.
10. .hdx - Help index.
11. .hex - Macintosh binary file./ Hex dump.
12. .hfi - GEM HP font info.
13. .hgl - HP graphics language graphic.
14. .hh - C++ Header.
15. .hhh - Precompiled Header for Power C.
16. .hhc - HTML Help Workshop Contents file.
17. .hhf - Hand Held Format file / HLA Header file.
18. .hhk - HTML Help Workshop Index file.
19. .hhp - HTML Help Workshop Project file./ Help data for Procomm Plus.
20. .hi - Descent 2 high score file.
21. .hlp - Windows standard help file./ Files that contain the Help feature used in windows, cannot be read from DOS.
22. .hmp - Music file.
23. .hog - Descent 1/2 archive file.
24. .hol - Microsoft Outlook Holiday file.
25. .hpp - C++ header file.
26. .hpgl - CAD file.
27. .hqx - Macintosh binary file./ Apple Macintosh Binhex text conversion file. Compressed file extracted and used with various compression utilities.
28. .hsq - Data files associated with the Qaz Trojan.
29. .hss - Photoshop Hue/Saturation information.
30. .hst - History file / Procomm Plus History File / Host file. 
31. .ht - HyperTerminal file.
32. .hta - Hypertext Application(run applications from HTML document).
33. .htm - HTML file./ Web page files containing HTML or other information found on the Internet.
34. .html - HTML file./ Web page files containing HTML or other information found on the Internet.
35. .htt - Folder settings file. Microsoft Hypertext Template file used with Microsoft Internet Explorer 4.0. The folder.htt is an example of this file type.
36. .hxm - Descent 2 game data attribute file.
37. .hxt - Hash extension plugin (Animation Master).
38. .hxx - C++ header file

Computer 'I' file extensions
1. .i00 - WinPhone phonebook / DVD Shrink.
2. .i - Borland C++ intermediary file.
3. .ic - ASwin project file.
4. .ica - Citrix file / IOCA graphics file.
5. .icb - Targa Bitmap.
6. .icc - Kodak printer image.
7. .ice - Archive file.
8. .icf - Information (Model) Configuration file / ICOM (CS-R20) communications file.
9. .icl - Icon Library File.
10. .icm - Image Color Matching profile.
11. .icn - Microsoft Windows Icon Manager.
12. .ico - Windows icon file.
13. .ics - Calendar data exchange file / SwiftView command file / IronCAD Scene file / Isochrone save file.
14. .id - MapInfo index file./ Disk identification file.
15. .idb - MS-Dev intermediate file./ Microsoft developer intermediate file, used with Microsoft Visual Studio.
16. .idd - MIDI instruments definition.
17. .ide - Integrated Development Environment configuration file.
18. .idf - MIDI instruments drivers file.
19. .idq - Internet data query file.
20. .idx - FoxPro index file / C-tree plus index file.
21. .if - CRwin project file.
22. .iff - IFF/LBM (Amiga) used by Computer Eyes frame grabber or Interchange File Format file.
23. .ifo - CD/DVD Information file.
24. .iif - QuickBooks import file.
25. .ima - IMA file format for medical images.
26. .img - GEM image file / CloneCD image file / CD image file / Erdas Hierarchical Image file / LinkSys firmware image file.
27. .imh - Incredimail email index file.
28. .imm - iMindMap mind-map file / IncrediMail e-mail file.
29. .imp - eBook import file / Simply Accounting file / Compressed archive / FileMaker Pro data filter / Desktop Dispatcher import file / WINGS GIS export file.
30. .in - GNU Autoconf configuration script.
31. .ind - MapInfo index file.
32. .inf - Information file that contains customization options.
33. .ini - Files that initialize Windows and Windows apps.
34. .ink - Mimio presentation / Pantone reference fills file.
35. .inl - Inline file.
36. .ins - Internet Naming Service file / InstallShield script.
37. .ipd - Blackberry backup information on PC.
38. .ipf - Installer Script File / OS/2 online documentation for Microsoft source files.
39. .isd - MySql data file.
40. .ism - MySql index file.
41. .iso - CD image file.
42. .iss - Inno Setup Script / InstallShield Silent response file.
43. .iw44 - DjVu File.
44. .iwa - IBM Writing Assistant Text file.
45. .iwp - Interactive web physics file / Wang WP file / Generated web page.

Computer 'J' file extensions
1. .j2k – JPEG 2000 file.
2. .jad - Java Application Descriptor.
3. .jar - Java Archive./ A compressed file used with ARJ Software and a compressed file containing Java packages and classes.
4. .jas - Graphic file.
5. .java - Java source file.
6. .jef - Janome embroidery file. Used in sewing and embroidery.
7. .jfif - JPEG graphics file.
8. .jgw - JPEG world file
9. .jhtm - Java Server page
10. .jhtml - Java Server page.
11. .jng - Multiple network graphics file.
12. .jnl - CVS journal file.
13. .job - Windows Task Scheduler Job / Tripod Data Systems job file / MetaCAM Nest job file.
14. .jp2 - JPEG 2000 file.
15. .jpc - JPEG 2000 file.
16. .jpg - JPEG graphics file.
17. .jpeg - JPEG graphics file.
18. .jpe - JPEG graphics file.
19. .jpm - JPEG 2000 file.
20. .jpr - JBuilder project file.
21. .jpx - JBuilder project file.
22. .jrs - Reserve transaction log file.
23. .js - JavaScript file.
24. .jsb - Henter-Joyce Jaws script binary file
25. .jsd - eFAX jet suite document
26. .jse - JScript encoded script file
27. .jsf - JourneyMan Session File / JavaServer Faces file.
28. .jsh - Henter-Joyce Jaws script header file
29. .jsl - PaintShop pro file
30. .jsm - Henter-Joyce Jaws script message file
31. .json - JSON data interchange file.
32. .jsp - Java server page
33. .jss - Henter-Joyce Jaws script source file
34. .jsp - Java Server page.
35. .jt – JT fax file
36. .jtf – JPEG tagged Interchange format file
37. .jtk – Sun Java toolkit file
38. .jtp – JetForm file
39. .jw - Justwrite text file
40. .jwl - Justwrite text file library
41. .jzz - Jazz spreadsheet

Computer 'K' file extensions
1. .k7 - MO5 tape image file.
2. .kar - Karaoke File used with some audio players.
3. .kbc - Netica case knowledge base.
4. .kdc - Kodak Photo-Enhancer file.
5. .kdp - KeePass password manager file.
6. .klb - F-Secure anti-virus signature update file.
7. .kfm - Keyframe Motion file (Animation Master).
8. .kfx - KoFaX image file.
9. .kml - Keyhole Markup Language file (Google Earth)
10. .kmz - Compressed keyhole markup language file.
11. .kye - Kye game data file.

Computer 'L' file extensions
1. .l - LEX source file
2. .lab - Excel mailing labels file / Codesoft Systems label software template file.
3. .lbl - Tharo Systems output label file.
4. .lbm - Interchange file format file.
5. .lbr - Library file (Animation Master).
6. .lbt - FoxPro label memo.
7. .lbx - FoxPro label.
8. .ldf - SQL Server database log file./ LuraDocument file.
9. .ldif - LDAP Data Interchange file / Netscape address book export.
10. .ldr - LDraw drawing file
11. .lgc - program Use Log File (for Windows Program Use Optimization).
12. .lgo - Windows start-up logo file./ Contains the code for displaying the screen logo.
13. .lha - Compressed file./ Compressed file extracted and used with various compression utilities.
14. .lib - Library file.
15. .lic - Component license file / Generic license file.
16. .lit - eBook / Light file.
17. .lnk - Windows shortcut./ Windows shortcut or a HTML link file used with Microsoft Internet Explorer
18. .log - Generic log file./ Contains the process of certain steps, such as when running scandisk it will usually keep a scandisk log of what occurred.
19. .log1 - Generic log file / Windows Registry hive log file.
20. .log2 - Generic log file / Windows registry hive log file.
21. .lsp - AutoCAD lisp program.
22. .lst - Listing file / FoxPro file / Playlist file / Kaspersky black-list file / PowerPoint play list file / SAS output listing file.
23. .lwf - LuraWave file.
24. .lwp - Lotus Wordpro 96/97 file.
25. .lyt - MetaCAM layout file.
26. .lzh - Compressed file./ Compressed file extracted and used with various compression Utilities

Computer 'M' file extensions
1. .m1v - MPEG movie.
2. .m2ts - Sony high definition video file.
3. .m3u - MP3 play list.
4. .m4a - Apple Inc MPEG 4 file.
5. .m4r - iPhone ringtone file.
6. .mac - Macintosh macpaint files.
7. .map - Linker map file / MapInfo file / Manifold project file.
8. .maq - Access query.
9. .mar - Access report.
10. .mat - Material file.
11. .max - PaperPort image file.
12. .mbm - MultiBitMap file.
13. .mbs - Opera mailbox / Multi bit series file / Master Bibliography style file / MR Tech Zip backup / Macrografx Picture Publisher Brush / Mailbag assistant script.
14. .mbx - Microsoft Outlook Express mailbox file.
15. .mcd - Motion capture plugin (Animation Master)./ MechaniCad Drawing.
16. .mco - MSN messenger winks file / XtraMusic file (tentative).
17. .md - Compressed Archive file
18. .md5 - Shorten audio checksum file / MD5 checksum file.
19. .mda - MicroDesign area file./ Microsoft Access Add-in / Microsoft Access 2 Workgroup.
20. .mdb - Microsoft Access Database / Microsoft Access  Application.
21. .mde - Access database (compiled).
22. .mdf - SQL Server database file / CD image file.
23. .mdl - Rose model file / Animation Master model file./ Digitrakker Music Module / Rational Rose / Quake model file
24. .mdm - Telix Modem Definition
25. .mdmp - Windows Minidump file.
26. .mdn - Microsoft Access Blank Database Template
27. .mdp - MicroDesign page file./ Microsoft Developer Studio Project
28. .mds - CD image file.
29. .mdt - Microsoft Access Add-in Data
30. .mdw - Microsoft Access Workgroup Information
31. .mdx - MapServer database index file / dBase index file./ dBase IV Multiple Index
32. .mdz - Microsoft Access Wizard Template
33. .meb - WordPerfect Macro Editor bottom overflow file
34. .med - WordPerfect Macro Editor delete save / OctaMed tracker module sound file.
35. .mem - WordPerfect Macro Editor macro / Memory File of variables
36. .mgl - Mascopt network graph file / plvdkey management summary file.
37. .mht - Web archive file.
38. .mhtml - Modular Hyper Text Mark-up Language web page / Web archive file.
39. .mid - MIDI file / MapInfo interchange file./ Midi orchestra files that are used to play with midi sounds built within the sound card.
40. .mif - MapInfo interchange file.
41. .mim - A MIME file./ MIME compressed file extracted and used with various compression utilities.
42. .mix - Power C object file / Command and Conquer file / PhotoDraw picture / Picture IT! picture / Dance eJay music mix.
43. .mkv - Matroska video file./ Short for Matroska, .MKV is similar to a .OGM file and is open source cross-platform movie file.
44. .mm - FreeMind mind map file / Matrix Market file.
45. .mma - Musical MIDI Accompaniment song file / Master Album Maker Album.
46. .mmap - MindManager mind-map file.
47. .mmd - Mail Message Download file
48. .mme - Compressed file extracted and used with various compression utilities.
49. .mn2 - Descent 2 mission file.
50. .mng - Multiple network graphics file.
51. .mod - Windows kernel module.
52. .modd - Picture Motion Browser data file.
53. .moff - Picture Motion Browser index file.
54. .mol - Molfile.
55. .mot - Motion file.
56. .mov - QuckTime movie.
57. .movie - Silicon Graphics movie.
58. .moz - Netscape cache file.
59. .mp1 - MPEG audio stream, layer I
60. .mp2 - MPEG 2 audio file.
61. .mp3 - MPEG 3 audio file.
62. .mp4 - MPEG 4 audio file.
63. .mpc - Musepack (audio) file.
64. .mpd - Multi Part Dat file.
65. .mpe - MPEG movie.
66. .mpeg - MPEG movie.
67. .mpg - MPEG movie.
68. .mpp - Microsoft Project file / CAD drawing file.
69. .mpt - Microsoft Project template file.
70. .mrw - Digital camera RAW file format.
71. .msc - MMC snap-in file / CRiSP fish stocks file./ Microsoft Common Console file.
72. .msdvd - Windows DVD Maker project file.
73. .mse - MSwinEHE project file.
74. .msf - Thunderbird Mail Summary file / Miranda IM skin file.
75. .msg - Outlook message file / Fidonet message.
76. .msi - System installer package.
77. .msm - System installer merge module.
78. .msn - Descent 1 mission file./ Microsoft Network document / Decent mission file
79. .msp - Microsoft System Installer Patch file / Midi Studio Project file.
80. .mspx - ASP.NET file.
81. .mst - Microsoft System Installer Transform file
82. .msv - Memory Stick Voice file / MyStars saved file.
83. .mtf  - Windows metafile.
84. .mth - Derive Math file
85. .mtm - Sound file / MultiTracker music module
86. .mtv - Picture file
87. .mtw - Minitab data file
88. .mu – Quattro menu
89. .mul – Ultima Online game
90. .mup – Music publisher file
91. .mus - Audio file
92. .mvl - Descent 2 movie archive.
93. .mvb - Database file / Microsoft multimedia viewer file
94. .mve - Interplay video file
95. .mvf - Movie stop frame file
96. .mwp - Lotus Wordpro 97 smartmaster file
97. .mws - MapInfo workspace file.
98. .mxd - ArcInfo map file
99. .mxt - Microsoft C Datafile
100. .mxml - Adobe Flex interface markup file.
101. .myd - MySQL data file / MyDefrag script./ Make your point presentation file.
102. .myi - MySQL index file.
......to be continued Part 2 Click Here

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