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

7Z file extension

7-Zip Compressed File

Compressed Files

LOG file extension

Log File

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

MDF file extension

Media Disc Image File

Disk Image Files

PIF file extension

Program Information File

Executable Files

JS file extension

JavaScript File

Web Files

BMP file extension

Bitmap Image File

Raster Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

ASX file extension

Microsoft ASF Redirector File

Video Files

JAVA file extension

Java Source Code File

Developer Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

GBR file extension

Gerber File

Data Files

SDF file extension

Standard Data File

Data Files

ROM file extension

N64 Game ROM File

Game Files