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

AI file extension

Adobe Illustrator File

Vector Image Files

ASF file extension

Advanced Systems Format File

Video Files

CPP file extension

C++ Source Code File

Developer Files

DLL file extension

Dynamic Link Library

System Files

HTML file extension

Hypertext Markup Language File

Web Files

ICO file extension

Icon File

System Files

INI file extension

Windows Initialization File

Settings Files

ODT file extension

OpenDocument Text Document

Text Files

PHP file extension

PHP Source Code File

Web Files

PRF file extension

Outlook Profile File

Settings Files

RA file extension

Real Audio File

Audio Files

TAR file extension

Consolidated Unix File Archive

Data Files

WMA file extension

Windows Media Audio File

Audio Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

3DM file extension

Rhino 3D Model

3D Image Files