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

ASF file extension

Advanced Systems Format File

Video Files

ASP file extension

Active Server Page

Web Files

CAB file extension

Windows Cabinet File

System Files

DAT file extension

Data File

Data Files

DBF file extension

Database File

Database Files

FLA file extension

Adobe Flash Animation

Developer Files

GPX file extension

GPS Exchange File

GIS Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

HTM file extension

Hypertext Markup Language File

Web Files

ICO file extension

Icon File

System Files

IFF file extension

Interchange File Format

Audio Files

MSG file extension

Outlook Mail Message

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

WSF file extension

Windows Script File

Executable Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files