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

CFG file extension

Configuration File

Settings Files

CLASS file extension

Java Class File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

GED file extension

GEDCOM Genealogy Data File

Data Files

KMZ file extension

Google Earth Placemark File

GIS Files

MDF file extension

Media Disc Image File

Disk Image Files

MP4 file extension

MPEG-4 Video File

Video Files

ODT file extension

OpenDocument Text Document

Text Files

PIF file extension

Program Information File

Executable Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PNG file extension

Portable Network Graphic

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files

VCXPROJ file extension

Visual C++ Project

Developer Files