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

AI file extension

Adobe Illustrator File

Vector Image Files

BAK file extension

Backup File

Backup Files

CER file extension

Internet Security Certificate

Web Files

CS file extension

Visual C# Source Code File

Developer Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ICS file extension

iCalendar File

Misc Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RSS file extension

Rich Site Summary

Web Files

SLN file extension

Visual Studio Solution File

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

TMP file extension

Temporary File

Backup Files

WMA file extension

Windows Media Audio File

Audio Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XML file extension

XML File

Data Files