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

APP file extension

Mac OS X Application

Executable Files

AVI file extension

Audio Video Interleave File

Video Files

BAT file extension

DOS Batch File

Executable Files

BMP file extension

Bitmap Image File

Raster Image Files

CPL file extension

Windows Control Panel Item

System Files

CSR file extension

Certificate Signing Request File

Web Files

FLV file extension

Flash Video File

Video Files

GPX file extension

GPS Exchange File

GIS Files

KML file extension

Keyhole Markup Language File

GIS Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

RA file extension

Real Audio File

Audio Files

VOB file extension

DVD Video Object File

Video Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files