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

CFM file extension

ColdFusion Markup File

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

PY file extension

Python Script

Developer Files

VOB file extension

DVD Video Object File

Video Files

VCXPROJ file extension

Visual C++ Project

Developer Files

PDB file extension

Program Database

Database Files

LOG file extension

Log File

Text Files

WSF file extension

Windows Script File

Executable Files

INDD file extension

Adobe InDesign Document

Layout Files

JS file extension

JavaScript File

Web Files

ICO file extension

Icon File

System Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PKG file extension

Mac OS X Installer Package

Compressed Files

BAT file extension

DOS Batch File

Executable Files

IFF file extension

Interchange File Format

Audio Files