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

SWF file extension

Shockwave Flash Movie

Video Files

TMP file extension

Temporary File

Backup Files

OTF file extension

OpenType Font

Font Files

DEB file extension

Debian Software Package

Compressed Files

TXT file extension

Plain Text File

Text Files

TIFF file extension

Tagged Image File Format

Raster Image Files

CUE file extension

Cue Sheet File

Disk Image Files

SAV file extension

Saved Game

Game Files

TIF file extension

Tagged Image File

Raster Image Files

MDB file extension

Microsoft Access Database

Database Files

7Z file extension

7-Zip Compressed File

Compressed Files

PAGES file extension

Pages Document

Text Files

IBOOKS file extension

Multi-Touch iBook

Data Files

ICO file extension

Icon File

System Files

XLR file extension

Works Spreadsheet

Spreadsheet Files