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

MSI file extension

Windows Installer Package

Misc Files

CBR file extension

Comic Book RAR Archive

Compressed Files

M file extension

Objective-C Implementation File

Developer Files

VOB file extension

DVD Video Object File

Video Files

MID file extension

MIDI File

Audio Files

RM file extension

Real Media File

Video Files

DB file extension

Database File

Database Files

GZ file extension

Gnu Zipped Archive

Compressed Files

KEY file extension

Keynote Presentation

Data Files

COM file extension

DOS Command File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

APK file extension

Android Package File

Executable Files

SWF file extension

Shockwave Flash Movie

Video Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

MP3 file extension

MP3 Audio File

Audio Files