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

CFG file extension

Configuration File

Settings Files

CSV file extension

Comma Separated Values File

Data Files

DEM file extension

Video Game Demo File

Game Files

DLL file extension

Dynamic Link Library

System Files

DMP file extension

Windows Memory Dump

System Files

H file extension

C/C++/Objective-C Header File

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

INI file extension

Windows Initialization File

Settings Files

M file extension

Objective-C Implementation File

Developer Files

MPG file extension

MPEG Video File

Video Files

NES file extension

Nintendo (NES) ROM File

Game Files

SRT file extension

SubRip Subtitle File

Video Files

TTF file extension

TrueType Font

Font Files

UUE file extension

Uuencoded File

Encoded Files

ZIPX file extension

Extended Zip File

Compressed Files