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

ASP file extension

Active Server Page

Web Files

C file extension

C/C++ Source Code File

Developer Files

CFG file extension

Configuration File

Settings Files

CGI file extension

Common Gateway Interface Script

Executable Files

CUE file extension

Cue Sheet File

Disk Image Files

DBF file extension

Database File

Database Files

M3U file extension

Media Playlist File

Audio Files

M4V file extension

iTunes Video File

Video Files

PAGES file extension

Pages Document

Text Files

PCT file extension

Picture File

Layout Files

PDB file extension

Program Database

Database Files

PHP file extension

PHP Source Code File

Web Files

TGA file extension

Targa Graphic

Raster Image Files

WPD file extension

WordPerfect Document

Text Files

3DM file extension

Rhino 3D Model

3D Image Files