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

DAT file extension

Data File

Data Files

DEM file extension

Video Game Demo File

Game Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

FNT file extension

Windows Font File

Font Files

INI file extension

Windows Initialization File

Settings Files

MPA file extension

MPEG-2 Audio File

Audio Files

MPG file extension

MPEG Video File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

ODT file extension

OpenDocument Text Document

Text Files

PAGES file extension

Pages Document

Text Files

PDF file extension

Portable Document Format File

Layout Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files

YUV file extension

YUV Encoded Image File

Raster Image Files