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

7Z file extension

7-Zip Compressed File

Compressed Files

MSG file extension

Outlook Mail Message

Text Files

ICS file extension

iCalendar File

Misc Files

VCD file extension

Virtual CD

Disk Image Files

PPS file extension

PowerPoint Slide Show

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

MAX file extension

3ds Max Scene File

3D Image Files

WMV file extension

Windows Media Video File

Video Files

SDF file extension

Standard Data File

Data Files

SWF file extension

Shockwave Flash Movie

Video Files

CFM file extension

ColdFusion Markup File

Web Files

ICO file extension

Icon File

System Files

DMP file extension

Windows Memory Dump

System Files

RSS file extension

Rich Site Summary

Web Files

RA file extension

Real Audio File

Audio Files