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

AIF file extension

Audio Interchange File Format

Audio Files

ASPX file extension

Active Server Page Extended File

Web Files

BAK file extension

Backup File

Backup Files

DOC# file extension

Microsoft Word Document

Text Files

EXE file extension

Windows Executable File

Executable Files

HTM file extension

Hypertext Markup Language File

Web Files

INI file extension

Windows Initialization File

Settings Files

JSP file extension

Java Server Page

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

PAGES file extension

Pages Document

Text Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VOB file extension

DVD Video Object File

Video Files

WMV file extension

Windows Media Video File

Video Files

3DS file extension

3D Studio Scene

3D Image Files