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

C file extension

C/C++ Source Code File

Developer Files

CGI file extension

Common Gateway Interface Script

Executable Files

CPL file extension

Windows Control Panel Item

System Files

DAT file extension

Data File

Data Files

DB file extension

Database File

Database Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GBR file extension

Gerber File

Data Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JS file extension

JavaScript File

Web Files

LOG file extension

Log File

Text Files

M file extension

Objective-C Implementation File

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

TMP file extension

Temporary File

Backup Files