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

CFG file extension

Configuration File

Settings Files

CFM file extension

ColdFusion Markup File

Web Files

CPP file extension

C++ Source Code File

Developer Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

JAR file extension

Java Archive File

Executable Files

JS file extension

JavaScript File

Web Files

M4V file extension

iTunes Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

PRF file extension

Outlook Profile File

Settings Files

SRT file extension

SubRip Subtitle File

Video Files

UUE file extension

Uuencoded File

Encoded Files

VCF file extension

vCard File

Data Files

VOB file extension

DVD Video Object File

Video Files

3DS file extension

3D Studio Scene

3D Image Files