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

ASX file extension

Microsoft ASF Redirector File

Video Files

AVI file extension

Audio Video Interleave File

Video Files

BMP file extension

Bitmap Image File

Raster Image Files

CER file extension

Internet Security Certificate

Web Files

DB file extension

Database File

Database Files

DDS file extension

DirectDraw Surface

Raster Image Files

DEB file extension

Debian Software Package

Compressed Files

FNT file extension

Windows Font File

Font Files

GBR file extension

Gerber File

Data Files

IBOOKS file extension

Multi-Touch iBook

Data Files

MSI file extension

Windows Installer Package

Misc Files

PS file extension

PostScript File

Vector Image Files

SDF file extension

Standard Data File

Data Files

SITX file extension

StuffIt X Archive

Compressed Files

VCF file extension

vCard File

Data Files