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

7Z file extension

7-Zip Compressed File

Compressed Files

TEX file extension

LaTeX Source Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

SITX file extension

StuffIt X Archive

Compressed Files

M3U file extension

Media Playlist File

Audio Files

FON file extension

Generic Font File

Font Files

BAK file extension

Backup File

Backup Files

ACCDB file extension

Access 2007 Database File

Database Files

SQL file extension

Structured Query Language Data File

Database Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

RSS file extension

Rich Site Summary

Web Files

CUR file extension

Windows Cursor

System Files

WPD file extension

WordPerfect Document

Text Files

RA file extension

Real Audio File

Audio Files