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

ASF file extension

Advanced Systems Format File

Video Files

BAK file extension

Backup File

Backup Files

CS file extension

Visual C# Source Code File

Developer Files

H file extension

C/C++/Objective-C Header File

Developer Files

IBOOKS file extension

Multi-Touch iBook

Data Files

KMZ file extension

Google Earth Placemark File

GIS Files

PDB file extension

Program Database

Database Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TIFF file extension

Tagged Image File Format

Raster Image Files

TTF file extension

TrueType Font

Font Files

VOB file extension

DVD Video Object File

Video Files

WSF file extension

Windows Script File

Executable Files