What is a file extension?
After naming a file, extensions are used to identify the type of a file. The extensions are added to the filename as a suffix with a dot representation(.) followed by one, two three or four characters. A file may have multiple extensions. Example:file.txt is a file name and .txt is its extension.
Why file extensions are used?
File extensions help an operating system to determine the program in which the file is associated. For example, file extensions starting with .m are often music or video formats such as .mov,.mp3,.mp4. These formats help the operating system to access the correct program quickly in the system.
List of file extensions that can’t be attached:
Some of the file extensions are blocked by default for uploading and downloading because those files may be executable files. Files with curly braces {} are also automatically blocked. The file extensions that are blocked by default are as follows
FILE EXTENSION |
FILE TYPE |
| .ade | Microsoft Access project extension |
| .adp | Microsoft Access project |
| .app | Application file |
| .asa | ASP declarations file |
| .ashx | ASP.NET Web handler file. Web handlers are software modules that handle raw HTTP requests received by ASP.NET. |
| .asmx | ASP.NET Web Services source file |
| .asp | Active Server Pages |
| .bas | Microsoft Visual Basic class module |
| .bat | Batch file |
| .cdx | Compound index |
| .cer | Certificate file |
| .chm | Compiled HTML Help file |
| .class | Java class file |
| .cmd | Microsoft Windows NT command script |
| .com | Microsoft MS-DOS program |
| .config | Configuration file |
| .cpl | Control Panel extension |
| .crt | Security certificate |
| .csh | Script file |
| .dll | Windows dynamic link library |
| .exe | Program |
| .fxp | Microsoft Visual FoxPro compiled program |
| .hlp | Help file |
| .hta | HTML program |
| .htr | Script file |
| .htw | HTML document |
| .ida | Internet Information Services file |
| .idc | Internet database connector file |
| .idq | Internet data query file |
| .ins | Internet Naming Service |
| .isp | Internet Communication settings |
| .its | Internet Document Set file |
| .jse | JScript Encoded script file |
| .ksh | Korn Shell script file |
| .lnk | Shortcut |
| .mad | Shortcut |
| .maf | Shortcut |
| .mag | Shortcut |
| .mam | Shortcut |
| .maq | Shortcut |
| .mar | Shortcut |
| .mas | Microsoft Access stored procedure |
| .mat | Shortcut |
| .mau | Shortcut |
| .mav | Shortcut |
| .maw | Shortcut |
| .mda | Microsoft Access add-in program |
| .mdb | Microsoft Access program |
| .mde | Microsoft Access MDE database |
| .mdt | Microsoft Access data file |
| .mdw | Microsoft Access workgroup |
| .mdz | Microsoft Access wizard program |
| .msc | Microsoft Common Console document |
| .msh | Microsoft Agent script helper |
| .msh1 | Microsoft Agent script helper |
| .msh1xml | Microsoft Agent script helper |
| .msh2 | Microsoft Agent script helper |
| .msh2xml | Microsoft Agent script helper |
| .mshxml | Microsoft Agent script helper |
| .msi | Microsoft Windows Installer package |
| .msp | Windows Installer patch package file |
| .mst | Visual Test source files |
| .ops | Microsoft Office profile settings file |
| .pcd | Photo CD image or Microsoft Visual Test compiled script |
| .pif | Shortcut to MS-DOS program |
| .prf | System file |
| .prg | Program source file |
| .printer | Printer file |
| .pst | Microsoft Outlook personal folder file |
| .reg | Registration entries |
| .rem | ACT! database maintenance file |
| .scf | Windows Explorer command file |
| .scr | Screen saver |
| .sct | Script file |
| .shb | Windows shortcut |
| .shs | Shell Scrap object |
| .shtm | HTML file that contains server side directives |
| .shtml | HTML file that contains server side directives |
| .soap | Simple Object Access Protocol file |
| .stm | HTML file that contains server side directives |
| .url | Uniform Resource Locator (Internet shortcut) |
| .vb | Microsoft Visual Basic Scripting Edition (Visual Basic Scripting Edition (VBScript)) file |
| .vbe | VBScript Encoded Script file |
| .vbs | VBScript file |
| .ws | Windows Script file |
| .wsc | Windows Script Component |
| .wsf | Windows Script file |
| .wsh | Windows Script Host settings file |