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

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

DLL file extension

Dynamic Link Library

System Files

DOC# file extension

Microsoft Word Document

Text Files

EPUB file extension

Open eBook File

eBook Files

GAM file extension

Saved Game File

Game Files

GZ file extension

Gnu Zipped Archive

Compressed Files

HTM file extension

Hypertext Markup Language File

Web Files

MOV file extension

Apple QuickTime Movie

Video Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

TGA file extension

Targa Graphic

Raster Image Files

VCF file extension

vCard File

Data Files

VOB file extension

DVD Video Object File

Video Files

XML file extension

XML File

Data Files