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

BAT file extension

DOS Batch File

Executable Files

CAB file extension

Windows Cabinet File

System Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DMP file extension

Windows Memory Dump

System Files

DRV file extension

Device Driver

System Files

DTD file extension

Document Type Definition File

Developer Files

PAGES file extension

Pages Document

Text Files

PART file extension

Partially Downloaded File

Misc Files

PPT file extension

PowerPoint Presentation

Data Files

PS file extension

PostScript File

Vector Image Files

SITX file extension

StuffIt X Archive

Compressed Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TGA file extension

Targa Graphic

Raster Image Files

WPD file extension

WordPerfect Document

Text Files

3DM file extension

Rhino 3D Model

3D Image Files