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

CRX file extension

Chrome Extension

Plugin Files

DEM file extension

Video Game Demo File

Game Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

EXE file extension

Windows Executable File

Executable Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

ICNS file extension

Mac OS X Icon Resource File

System Files

M4A file extension

MPEG-4 Audio File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

SH file extension

Bash Shell Script

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3DS file extension

3D Studio Scene

3D Image Files