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

BMP file extension

Bitmap Image File

Raster Image Files

WMA file extension

Windows Media Audio File

Audio Files

LOG file extension

Log File

Text Files

VCXPROJ file extension

Visual C++ Project

Developer Files

DRV file extension

Device Driver

System Files

H file extension

C/C++/Objective-C Header File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

DBF file extension

Database File

Database Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

YUV file extension

YUV Encoded Image File

Raster Image Files

CLASS file extension

Java Class File

Developer Files

ICNS file extension

Mac OS X Icon Resource File

System Files

RTF file extension

Rich Text Format File

Text Files

CS file extension

Visual C# Source Code File

Developer Files

GADGET file extension

Windows Gadget

Executable Files