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

APP file extension

Mac OS X Application

Executable Files

BAT file extension

DOS Batch File

Executable Files

CFG file extension

Configuration File

Settings Files

CGI file extension

Common Gateway Interface Script

Executable Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CRX file extension

Chrome Extension

Plugin Files

ICO file extension

Icon File

System Files

KML file extension

Keyhole Markup Language File

GIS Files

MP4 file extension

MPEG-4 Video File

Video Files

PDB file extension

Program Database

Database Files

PRF file extension

Outlook Profile File

Settings Files

RM file extension

Real Media File

Video Files

TORRENT file extension

BitTorrent File

Misc Files

TXT file extension

Plain Text File

Text Files

YUV file extension

YUV Encoded Image File

Raster Image Files