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

ICNS file extension

Mac OS X Icon Resource File

System Files

ODT file extension

OpenDocument Text Document

Text Files

MPG file extension

MPEG Video File

Video Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DDS file extension

DirectDraw Surface

Raster Image Files

OTF file extension

OpenType Font

Font Files

7Z file extension

7-Zip Compressed File

Compressed Files

KEY file extension

Keynote Presentation

Data Files

AVI file extension

Audio Video Interleave File

Video Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

FLA file extension

Adobe Flash Animation

Developer Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

TGA file extension

Targa Graphic

Raster Image Files

M4A file extension

MPEG-4 Audio File

Audio Files