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

ASX file extension

Microsoft ASF Redirector File

Video Files

CGI file extension

Common Gateway Interface Script

Executable Files

DB file extension

Database File

Database Files

DBF file extension

Database File

Database Files

DEB file extension

Debian Software Package

Compressed Files

DEM file extension

Video Game Demo File

Game Files

FLA file extension

Adobe Flash Animation

Developer Files

GZ file extension

Gnu Zipped Archive

Compressed Files

M4V file extension

iTunes Video File

Video Files

MDF file extension

Media Disc Image File

Disk Image Files

MPG file extension

MPEG Video File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PHP file extension

PHP Source Code File

Web Files

TARGZ file extension

Compressed Tarball File

Compressed Files