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

ACCDB file extension

Access 2007 Database File

Database Files

AVI file extension

Audio Video Interleave File

Video Files

BAK file extension

Backup File

Backup Files

CPL file extension

Windows Control Panel Item

System Files

H file extension

C/C++/Objective-C Header File

Developer Files

PL file extension

Perl Script

Developer Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

RTF file extension

Rich Text Format File

Text Files

SAV file extension

Saved Game

Game Files

SYS file extension

Windows System File

System Files

TXT file extension

Plain Text File

Text Files

UUE file extension

Uuencoded File

Encoded Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files