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

KML file extension

Keyhole Markup Language File

GIS Files

CER file extension

Internet Security Certificate

Web Files

ZIPX file extension

Extended Zip File

Compressed Files

DMP file extension

Windows Memory Dump

System Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

WAV file extension

WAVE Audio File

Audio Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TIF file extension

Tagged Image File

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

SQL file extension

Structured Query Language Data File

Database Files

M3U file extension

Media Playlist File

Audio Files