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

AVI file extension

Audio Video Interleave File

Video Files

CRX file extension

Chrome Extension

Plugin 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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

KMZ file extension

Google Earth Placemark File

GIS Files

LOG file extension

Log File

Text Files

PART file extension

Partially Downloaded File

Misc Files

PCT file extension

Picture File

Layout Files

PY file extension

Python Script

Developer Files

RM file extension

Real Media File

Video Files

SQL file extension

Structured Query Language Data File

Database Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files