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

ACCDB file extension

Access 2007 Database File

Database Files

AZW file extension

Amazon Kindle eBook File

eBook Files

BAK file extension

Backup File

Backup Files

CFM file extension

ColdFusion Markup File

Web Files

ICS file extension

iCalendar File

Misc Files

INI file extension

Windows Initialization File

Settings Files

JS file extension

JavaScript File

Web Files

KMZ file extension

Google Earth Placemark File

GIS Files

MOV file extension

Apple QuickTime Movie

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TORRENT file extension

BitTorrent File

Misc Files

WMV file extension

Windows Media Video File

Video Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3GP file extension

3GPP Multimedia File

Video Files