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

ASF file extension

Advanced Systems Format File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files

ZIP file extension

Zipped File

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

CAB file extension

Windows Cabinet File

System Files

SAV file extension

Saved Game

Game Files

MID file extension

MIDI File

Audio Files

ASP file extension

Active Server Page

Web Files

VB file extension

VBScript File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

PDF file extension

Portable Document Format File

Layout Files

IFF file extension

Interchange File Format

Audio Files

CPP file extension

C++ Source Code File

Developer Files

M file extension

Objective-C Implementation File

Developer Files

ISO file extension

Disc Image File

Disk Image Files