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

CGI file extension

Common Gateway Interface Script

Executable Files

CSR file extension

Certificate Signing Request File

Web Files

CSV file extension

Comma Separated Values File

Data Files

CUE file extension

Cue Sheet File

Disk Image Files

DEM file extension

Video Game Demo File

Game Files

DXF file extension

Drawing Exchange Format File

CAD Files

GADGET file extension

Windows Gadget

Executable Files

JS file extension

JavaScript File

Web Files

MAX file extension

3ds Max Scene File

3D Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SAV file extension

Saved Game

Game Files

SYS file extension

Windows System File

System Files

TARGZ file extension

Compressed Tarball File

Compressed Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3GP file extension

3GPP Multimedia File

Video Files