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

BIN file extension

Binary Disc Image

Disk Image Files

CSS file extension

Cascading Style Sheet

Web Files

DLL file extension

Dynamic Link Library

System Files

DOC file extension

Microsoft Word Document

Text Files

GBR file extension

Gerber File

Data Files

GPX file extension

GPS Exchange File

GIS Files

M4V file extension

iTunes Video File

Video Files

MPG file extension

MPEG Video File

Video Files

PIF file extension

Program Information File

Executable Files

RM file extension

Real Media File

Video Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

SRT file extension

SubRip Subtitle File

Video Files

TORRENT file extension

BitTorrent File

Misc Files

3GP file extension

3GPP Multimedia File

Video Files