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

BAK file extension

Backup File

Backup Files

DB file extension

Database File

Database Files

DEM file extension

Video Game Demo File

Game Files

DMP file extension

Windows Memory Dump

System Files

GADGET file extension

Windows Gadget

Executable Files

GZ file extension

Gnu Zipped Archive

Compressed Files

IFF file extension

Interchange File Format

Audio Files

JAVA file extension

Java Source Code File

Developer Files

JS file extension

JavaScript File

Web Files

MP4 file extension

MPEG-4 Video File

Video Files

MSG file extension

Outlook Mail Message

Text Files

PDB file extension

Program Database

Database Files

RM file extension

Real Media File

Video Files

SAV file extension

Saved Game

Game Files

TAR file extension

Consolidated Unix File Archive

Data Files