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

RSS file extension

Rich Site Summary

Web Files

ASF file extension

Advanced Systems Format File

Video Files

PAGES file extension

Pages Document

Text Files

DOC file extension

Microsoft Word Document

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

WAV file extension

WAVE Audio File

Audio Files

FLA file extension

Adobe Flash Animation

Developer Files

VCF file extension

vCard File

Data Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

AVI file extension

Audio Video Interleave File

Video Files

ASP file extension

Active Server Page

Web Files

EXE file extension

Windows Executable File

Executable Files

DLL file extension

Dynamic Link Library

System Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files