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

WPS file extension

Microsoft Works Word Processor Document

Text Files

CSV file extension

Comma Separated Values File

Data Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

PART file extension

Partially Downloaded File

Misc Files

VOB file extension

DVD Video Object File

Video Files

CFG file extension

Configuration File

Settings Files

DDS file extension

DirectDraw Surface

Raster Image Files

TIF file extension

Tagged Image File

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

PCT file extension

Picture File

Layout Files

ICO file extension

Icon File

System Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JS file extension

JavaScript File

Web Files

3DS file extension

3D Studio Scene

3D Image Files