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

ASP file extension

Active Server Page

Web Files

BAK file extension

Backup File

Backup Files

DLL file extension

Dynamic Link Library

System Files

DTD file extension

Document Type Definition File

Developer Files

FNT file extension

Windows Font File

Font Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICO file extension

Icon File

System Files

JAR file extension

Java Archive File

Executable Files

JS file extension

JavaScript File

Web Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPT file extension

PowerPoint Presentation

Data Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

WMA file extension

Windows Media Audio File

Audio Files