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

NES file extension

Nintendo (NES) ROM File

Game Files

JAVA file extension

Java Source Code File

Developer Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

DLL file extension

Dynamic Link Library

System Files

FLA file extension

Adobe Flash Animation

Developer Files

MDF file extension

Media Disc Image File

Disk Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

TORRENT file extension

BitTorrent File

Misc Files

CSS file extension

Cascading Style Sheet

Web Files

DAT file extension

Data File

Data Files

IFF file extension

Interchange File Format

Audio Files

PIF file extension

Program Information File

Executable Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

PNG file extension

Portable Network Graphic

Raster Image Files