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

CFM file extension

ColdFusion Markup File

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

CLASS file extension

Java Class File

Developer Files

DAT file extension

Data File

Data Files

FLV file extension

Flash Video File

Video Files

ICO file extension

Icon File

System Files

JAR file extension

Java Archive File

Executable Files

KML file extension

Keyhole Markup Language File

GIS Files

MID file extension

MIDI File

Audio Files

MSG file extension

Outlook Mail Message

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

RA file extension

Real Audio File

Audio Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SH file extension

Bash Shell Script

Developer Files

TIFF file extension

Tagged Image File Format

Raster Image Files