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

ASPX file extension

Active Server Page Extended File

Web Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CBR file extension

Comic Book RAR Archive

Compressed Files

COM file extension

DOS Command File

Executable Files

DEB file extension

Debian Software Package

Compressed Files

ICS file extension

iCalendar File

Misc Files

M3U file extension

Media Playlist File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MOV file extension

Apple QuickTime Movie

Video Files

PDF file extension

Portable Document Format File

Layout Files

RA file extension

Real Audio File

Audio Files

RSS file extension

Rich Site Summary

Web Files

SITX file extension

StuffIt X Archive

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

VCF file extension

vCard File

Data Files