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

BAK file extension

Backup File

Backup Files

BMP file extension

Bitmap Image File

Raster Image Files

CER file extension

Internet Security Certificate

Web Files

DBF file extension

Database File

Database Files

DEB file extension

Debian Software Package

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JS file extension

JavaScript File

Web Files

M3U file extension

Media Playlist File

Audio Files

MID file extension

MIDI File

Audio Files

RTF file extension

Rich Text Format File

Text Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TEX file extension

LaTeX Source Document

Text Files

TGA file extension

Targa Graphic

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files