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

AVI file extension

Audio Video Interleave File

Video Files

CSR file extension

Certificate Signing Request File

Web Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

HTML file extension

Hypertext Markup Language File

Web Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ICO file extension

Icon File

System Files

M4V file extension

iTunes Video File

Video Files

MAX file extension

3ds Max Scene File

3D Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

NES file extension

Nintendo (NES) ROM File

Game Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SLN file extension

Visual Studio Solution File

Developer Files

WPS file extension

Microsoft Works Word Processor Document

Text Files