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

ASX file extension

Microsoft ASF Redirector File

Video Files

CPP file extension

C++ Source Code File

Developer Files

DTD file extension

Document Type Definition File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

MDB file extension

Microsoft Access Database

Database Files

MOV file extension

Apple QuickTime Movie

Video Files

ODT file extension

OpenDocument Text Document

Text Files

PPS file extension

PowerPoint Slide Show

Data Files

SYS file extension

Windows System File

System Files

TXT file extension

Plain Text File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WAV file extension

WAVE Audio File

Audio Files

YUV file extension

YUV Encoded Image File

Raster Image Files

ZIPX file extension

Extended Zip File

Compressed Files

3DS file extension

3D Studio Scene

3D Image Files