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

CBR file extension

Comic Book RAR Archive

Compressed Files

CLASS file extension

Java Class File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

FNT file extension

Windows Font File

Font Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

IFF file extension

Interchange File Format

Audio Files

JPG file extension

JPEG Image

Raster Image Files

LNK file extension

Windows File Shortcut

System Files

M4V file extension

iTunes Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

TTF file extension

TrueType Font

Font Files

WAV file extension

WAVE Audio File

Audio Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files