File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

H file extension

C/C++/Objective-C Header File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

COM file extension

DOS Command File

Executable Files

ODT file extension

OpenDocument Text Document

Text Files

CGI file extension

Common Gateway Interface Script

Executable Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

ACCDB file extension

Access 2007 Database File

Database Files

7Z file extension

7-Zip Compressed File

Compressed Files

CRX file extension

Chrome Extension

Plugin Files

DDS file extension

DirectDraw Surface

Raster Image Files

PNG file extension

Portable Network Graphic

Raster Image Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

APK file extension

Android Package File

Executable Files

GPX file extension

GPS Exchange File

GIS Files

DRV file extension

Device Driver

System Files