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

DOCX file extension

Microsoft Word Open XML Document

Text Files

TOAST file extension

Toast Disc Image

Disk Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DEM file extension

Video Game Demo File

Game Files

BAT file extension

DOS Batch File

Executable Files

M4V file extension

iTunes Video File

Video Files

VCXPROJ file extension

Visual C++ Project

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

AZW file extension

Amazon Kindle eBook File

eBook Files

JPG file extension

JPEG Image

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

CPL file extension

Windows Control Panel Item

System Files

CGI file extension

Common Gateway Interface Script

Executable Files

SDF file extension

Standard Data File

Data Files

PDB file extension

Program Database

Database Files