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

CRX file extension

Chrome Extension

Plugin Files

CSR file extension

Certificate Signing Request File

Web Files

CUR file extension

Windows Cursor

System Files

DDS file extension

DirectDraw Surface

Raster Image Files

DEM file extension

Video Game Demo File

Game Files

M4A file extension

MPEG-4 Audio File

Audio Files

M4V file extension

iTunes Video File

Video Files

MP3 file extension

MP3 Audio File

Audio Files

PART file extension

Partially Downloaded File

Misc Files

PRF file extension

Outlook Profile File

Settings Files

SYS file extension

Windows System File

System Files

VB file extension

VBScript File

Executable Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files