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

CER file extension

Internet Security Certificate

Web Files

CPL file extension

Windows Control Panel Item

System Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DLL file extension

Dynamic Link Library

System Files

DOC file extension

Microsoft Word Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

FLA file extension

Adobe Flash Animation

Developer Files

LNK file extension

Windows File Shortcut

System Files

MAX file extension

3ds Max Scene File

3D Image Files

PL file extension

Perl Script

Developer Files

ROM file extension

N64 Game ROM File

Game Files

RSS file extension

Rich Site Summary

Web Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TGA file extension

Targa Graphic

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files