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

ISO file extension

Disc Image File

Disk Image Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

JS file extension

JavaScript File

Web Files

ROM file extension

N64 Game ROM File

Game Files

DXF file extension

Drawing Exchange Format File

CAD Files

CAB file extension

Windows Cabinet File

System Files

TTF file extension

TrueType Font

Font Files

DNG file extension

Digital Negative Image File

Camera Raw Files

CBR file extension

Comic Book RAR Archive

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JSP file extension

Java Server Page

Web Files

LOG file extension

Log File

Text Files

GZ file extension

Gnu Zipped Archive

Compressed Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files