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

DBF file extension

Database File

Database Files

EXE file extension

Windows Executable File

Executable Files

ICNS file extension

Mac OS X Icon Resource File

System Files

INDD file extension

Adobe InDesign Document

Layout Files

ISO file extension

Disc Image File

Disk Image Files

JSP file extension

Java Server Page

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

MOV file extension

Apple QuickTime Movie

Video Files

PAGES file extension

Pages Document

Text Files

PPS file extension

PowerPoint Slide Show

Data Files

PS file extension

PostScript File

Vector Image Files

SITX file extension

StuffIt X Archive

Compressed Files

TMP file extension

Temporary File

Backup Files

WMA file extension

Windows Media Audio File

Audio Files

YUV file extension

YUV Encoded Image File

Raster Image Files