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

ASX file extension

Microsoft ASF Redirector File

Video Files

CS file extension

Visual C# Source Code File

Developer Files

EXE file extension

Windows Executable File

Executable Files

H file extension

C/C++/Objective-C Header File

Developer Files

KMZ file extension

Google Earth Placemark File

GIS Files

PPT file extension

PowerPoint Presentation

Data Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

ROM file extension

N64 Game ROM File

Game Files

SYS file extension

Windows System File

System Files

TAR file extension

Consolidated Unix File Archive

Data Files

UUE file extension

Uuencoded File

Encoded Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files