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

C file extension

C/C++ Source Code File

Developer Files

CFG file extension

Configuration File

Settings Files

CSV file extension

Comma Separated Values File

Data Files

DMP file extension

Windows Memory Dump

System Files

GPX file extension

GPS Exchange File

GIS Files

ICO file extension

Icon File

System Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MDF file extension

Media Disc Image File

Disk Image Files

PART file extension

Partially Downloaded File

Misc Files

ROM file extension

N64 Game ROM File

Game Files

SH file extension

Bash Shell Script

Developer Files

TOAST file extension

Toast Disc Image

Disk Image Files

VCXPROJ file extension

Visual C++ Project

Developer Files

VOB file extension

DVD Video Object File

Video Files

WMV file extension

Windows Media Video File

Video Files