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

ASPX file extension

Active Server Page Extended File

Web Files

BMP file extension

Bitmap Image File

Raster Image Files

CFM file extension

ColdFusion Markup File

Web Files

DAT file extension

Data File

Data Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

FLA file extension

Adobe Flash Animation

Developer Files

HTML file extension

Hypertext Markup Language File

Web Files

INI file extension

Windows Initialization File

Settings Files

MDF file extension

Media Disc Image File

Disk Image Files

MPA file extension

MPEG-2 Audio File

Audio Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RSS file extension

Rich Site Summary

Web Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

XML file extension

XML File

Data Files