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

ASP file extension

Active Server Page

Web Files

CFG file extension

Configuration File

Settings Files

CGI file extension

Common Gateway Interface Script

Executable Files

CSS file extension

Cascading Style Sheet

Web Files

DEB file extension

Debian Software Package

Compressed Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

ICS file extension

iCalendar File

Misc Files

MAX file extension

3ds Max Scene File

3D Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MSI file extension

Windows Installer Package

Misc Files

PL file extension

Perl Script

Developer Files

RM file extension

Real Media File

Video Files

TGA file extension

Targa Graphic

Raster Image Files

VOB file extension

DVD Video Object File

Video Files

ZIPX file extension

Extended Zip File

Compressed Files