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

BIN file extension

Binary Disc Image

Disk Image Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSS file extension

Cascading Style Sheet

Web Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

JAR file extension

Java Archive File

Executable Files

JS file extension

JavaScript File

Web Files

MPG file extension

MPEG Video File

Video Files

MSG file extension

Outlook Mail Message

Text Files

NES file extension

Nintendo (NES) ROM File

Game Files

PART file extension

Partially Downloaded File

Misc Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

TEX file extension

LaTeX Source Document

Text Files

TXT file extension

Plain Text File

Text Files