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

CLASS file extension

Java Class File

Developer Files

COM file extension

DOS Command File

Executable Files

DEM file extension

Video Game Demo File

Game Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DRV file extension

Device Driver

System Files

H file extension

C/C++/Objective-C Header File

Developer Files

JPG file extension

JPEG Image

Raster Image Files

M4A file extension

MPEG-4 Audio File

Audio Files

MDB file extension

Microsoft Access Database

Database Files

MOV file extension

Apple QuickTime Movie

Video Files

MSG file extension

Outlook Mail Message

Text Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TAR file extension

Consolidated Unix File Archive

Data Files

VCD file extension

Virtual CD

Disk Image Files

ZIP file extension

Zipped File

Compressed Files