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

MID file extension

MIDI File

Audio Files

LNK file extension

Windows File Shortcut

System Files

WMA file extension

Windows Media Audio File

Audio Files

GZ file extension

Gnu Zipped Archive

Compressed Files

JS file extension

JavaScript File

Web Files

BAT file extension

DOS Batch File

Executable Files

KEY file extension

Keynote Presentation

Data Files

LUA file extension

Lua Source File

Developer Files

SYS file extension

Windows System File

System Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

C file extension

C/C++ Source Code File

Developer Files

AVI file extension

Audio Video Interleave File

Video Files

PNG file extension

Portable Network Graphic

Raster Image Files

CPP file extension

C++ Source Code File

Developer Files