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

AIF file extension

Audio Interchange File Format

Audio Files

CAB file extension

Windows Cabinet File

System Files

DB file extension

Database File

Database Files

DLL file extension

Dynamic Link Library

System Files

GADGET file extension

Windows Gadget

Executable Files

INI file extension

Windows Initialization File

Settings Files

JPG file extension

JPEG Image

Raster Image Files

MAX file extension

3ds Max Scene File

3D Image Files

RSS file extension

Rich Site Summary

Web Files

SWF file extension

Shockwave Flash Movie

Video Files

TAR file extension

Consolidated Unix File Archive

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

VCD file extension

Virtual CD

Disk Image Files

WMA file extension

Windows Media Audio File

Audio Files

ZIPX file extension

Extended Zip File

Compressed Files