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

JS file extension

JavaScript File

Web Files

SDF file extension

Standard Data File

Data Files

MAX file extension

3ds Max Scene File

3D Image Files

INDD file extension

Adobe InDesign Document

Layout Files

TOAST file extension

Toast Disc Image

Disk Image Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

PDB file extension

Program Database

Database Files

BMP file extension

Bitmap Image File

Raster Image Files

BAK file extension

Backup File

Backup Files

GBR file extension

Gerber File

Data Files

C file extension

C/C++ Source Code File

Developer Files

APP file extension

Mac OS X Application

Executable Files

TORRENT file extension

BitTorrent File

Misc Files

WAV file extension

WAVE Audio File

Audio Files