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

AIF file extension

Audio Interchange File Format

Audio Files

BAK file extension

Backup File

Backup Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CS file extension

Visual C# Source Code File

Developer Files

DBF file extension

Database File

Database Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAVA file extension

Java Source Code File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

MAX file extension

3ds Max Scene File

3D Image Files

MID file extension

MIDI File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

SITX file extension

StuffIt X Archive

Compressed Files

UUE file extension

Uuencoded File

Encoded Files