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

TARGZ file extension

Compressed Tarball File

Compressed Files

BAT file extension

DOS Batch File

Executable Files

DDS file extension

DirectDraw Surface

Raster Image Files

CPP file extension

C++ Source Code File

Developer Files

OTF file extension

OpenType Font

Font Files

HTML file extension

Hypertext Markup Language File

Web Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

VCF file extension

vCard File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

MSG file extension

Outlook Mail Message

Text Files

ZIPX file extension

Extended Zip File

Compressed Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

PS file extension

PostScript File

Vector Image Files

WMA file extension

Windows Media Audio File

Audio Files