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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOC# file extension

Microsoft Word Document

Text Files

FLV file extension

Flash Video File

Video Files

FON file extension

Generic Font File

Font Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

KEY file extension

Keynote Presentation

Data Files

PAGES file extension

Pages Document

Text Files

SRT file extension

SubRip Subtitle File

Video Files

TAR file extension

Consolidated Unix File Archive

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

TTF file extension

TrueType Font

Font Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

3G2 file extension

3GPP2 Multimedia File

Video Files