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

3GP file extension

3GPP Multimedia File

Video Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

DTD file extension

Document Type Definition File

Developer Files

FON file extension

Generic Font File

Font Files

WMA file extension

Windows Media Audio File

Audio Files

APK file extension

Android Package File

Executable Files

PCT file extension

Picture File

Layout Files

DMP file extension

Windows Memory Dump

System Files

SDF file extension

Standard Data File

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

MSI file extension

Windows Installer Package

Misc Files

7Z file extension

7-Zip Compressed File

Compressed Files

FLV file extension

Flash Video File

Video Files

GIF file extension

Graphical Interchange Format File

Raster Image Files