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

DDS file extension

DirectDraw Surface

Raster Image Files

FNT file extension

Windows Font File

Font Files

INI file extension

Windows Initialization File

Settings Files

JS file extension

JavaScript File

Web Files

MPA file extension

MPEG-2 Audio File

Audio Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

SWF file extension

Shockwave Flash Movie

Video Files

SYS file extension

Windows System File

System Files

VCXPROJ file extension

Visual C++ Project

Developer Files

WMA file extension

Windows Media Audio File

Audio Files

WSF file extension

Windows Script File

Executable Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files