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

CAB file extension

Windows Cabinet File

System Files

DAT file extension

Data File

Data Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

FON file extension

Generic Font File

Font Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

JAR file extension

Java Archive File

Executable Files

M4V file extension

iTunes Video File

Video Files

MPG file extension

MPEG Video File

Video Files

PHP file extension

PHP Source Code File

Web Files

RM file extension

Real Media File

Video Files

RSS file extension

Rich Site Summary

Web Files

TARGZ file extension

Compressed Tarball File

Compressed Files

UUE file extension

Uuencoded File

Encoded Files

VCF file extension

vCard File

Data Files

3DS file extension

3D Studio Scene

3D Image Files