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

AZW file extension

Amazon Kindle eBook File

eBook Files

KML file extension

Keyhole Markup Language File

GIS Files

7Z file extension

7-Zip Compressed File

Compressed Files

ZIP file extension

Zipped File

Compressed Files

PY file extension

Python Script

Developer Files

ASP file extension

Active Server Page

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

WMA file extension

Windows Media Audio File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

CRX file extension

Chrome Extension

Plugin Files

CS file extension

Visual C# Source Code File

Developer Files

INI file extension

Windows Initialization File

Settings Files

AVI file extension

Audio Video Interleave File

Video Files

DRV file extension

Device Driver

System Files

DAT file extension

Data File

Data Files