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

ASP file extension

Active Server Page

Web Files

DB file extension

Database File

Database Files

FON file extension

Generic Font File

Font Files

IBOOKS file extension

Multi-Touch iBook

Data Files

IFF file extension

Interchange File Format

Audio Files

MAX file extension

3ds Max Scene File

3D Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPG file extension

MPEG Video File

Video Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RM file extension

Real Media File

Video Files

SWF file extension

Shockwave Flash Movie

Video Files

WSF file extension

Windows Script File

Executable Files

XCODEPROJ file extension

Xcode Project

Developer Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3GP file extension

3GPP Multimedia File

Video Files