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

ASPX file extension

Active Server Page Extended File

Web Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CRX file extension

Chrome Extension

Plugin Files

DEM file extension

Video Game Demo File

Game Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FLV file extension

Flash Video File

Video Files

INDD file extension

Adobe InDesign Document

Layout Files

JAR file extension

Java Archive File

Executable Files

MDF file extension

Media Disc Image File

Disk Image Files

NES file extension

Nintendo (NES) ROM File

Game Files

PHP file extension

PHP Source Code File

Web Files

RM file extension

Real Media File

Video Files

SH file extension

Bash Shell Script

Developer Files

WSF file extension

Windows Script File

Executable Files

ZIPX file extension

Extended Zip File

Compressed Files