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

CUR file extension

Windows Cursor

System Files

DLL file extension

Dynamic Link Library

System Files

FNT file extension

Windows Font File

Font Files

IFF file extension

Interchange File Format

Audio Files

INI file extension

Windows Initialization File

Settings Files

MAX file extension

3ds Max Scene File

3D Image Files

MOV file extension

Apple QuickTime Movie

Video Files

MP3 file extension

MP3 Audio File

Audio Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SITX file extension

StuffIt X Archive

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files

VB file extension

VBScript File

Executable Files

WAV file extension

WAVE Audio File

Audio Files

WPS file extension

Microsoft Works Word Processor Document

Text Files