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

JPG file extension

JPEG Image

Raster Image Files

JAR file extension

Java Archive File

Executable Files

ASPX file extension

Active Server Page Extended File

Web Files

DEM file extension

Video Game Demo File

Game Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

LOG file extension

Log File

Text Files

RSS file extension

Rich Site Summary

Web Files

CAB file extension

Windows Cabinet File

System Files

WAV file extension

WAVE Audio File

Audio Files

GAM file extension

Saved Game File

Game Files

7Z file extension

7-Zip Compressed File

Compressed Files

FLA file extension

Adobe Flash Animation

Developer Files

MSG file extension

Outlook Mail Message

Text Files

SYS file extension

Windows System File

System Files

3DM file extension

Rhino 3D Model

3D Image Files