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

AZW file extension

Amazon Kindle eBook File

eBook Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

DDS file extension

DirectDraw Surface

Raster Image Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

GPX file extension

GPS Exchange File

GIS Files

LUA file extension

Lua Source File

Developer Files

MOBI file extension

Mobipocket eBook

eBook Files

MSG file extension

Outlook Mail Message

Text Files

OTF file extension

OpenType Font

Font Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files