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

CFM file extension

ColdFusion Markup File

Web Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

DEB file extension

Debian Software Package

Compressed Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

DXF file extension

Drawing Exchange Format File

CAD Files

INDD file extension

Adobe InDesign Document

Layout Files

ISO file extension

Disc Image File

Disk Image Files

KML file extension

Keyhole Markup Language File

GIS Files

PCT file extension

Picture File

Layout Files

PHP file extension

PHP Source Code File

Web Files

RM file extension

Real Media File

Video Files

TMP file extension

Temporary File

Backup Files

WSF file extension

Windows Script File

Executable Files

3GP file extension

3GPP Multimedia File

Video Files