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

AVI file extension

Audio Video Interleave File

Video Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CFG file extension

Configuration File

Settings Files

DLL file extension

Dynamic Link Library

System Files

DTD file extension

Document Type Definition File

Developer Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GAM file extension

Saved Game File

Game Files

ICNS file extension

Mac OS X Icon Resource File

System Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PART file extension

Partially Downloaded File

Misc Files

PHP file extension

PHP Source Code File

Web Files

TORRENT file extension

BitTorrent File

Misc Files

VOB file extension

DVD Video Object File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files