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

ASX file extension

Microsoft ASF Redirector File

Video Files

PIF file extension

Program Information File

Executable Files

CS file extension

Visual C# Source Code File

Developer Files

WSF file extension

Windows Script File

Executable Files

FLA file extension

Adobe Flash Animation

Developer Files

PKG file extension

Mac OS X Installer Package

Compressed Files

M4V file extension

iTunes Video File

Video Files

VCD file extension

Virtual CD

Disk Image Files

BAK file extension

Backup File

Backup Files

CGI file extension

Common Gateway Interface Script

Executable Files

INDD file extension

Adobe InDesign Document

Layout Files

EXE file extension

Windows Executable File

Executable Files

WAV file extension

WAVE Audio File

Audio Files

RM file extension

Real Media File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files