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

BIN file extension

Binary Disc Image

Disk Image Files

CFM file extension

ColdFusion Markup File

Web Files

COM file extension

DOS Command File

Executable Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GED file extension

GEDCOM Genealogy Data File

Data Files

GPX file extension

GPS Exchange File

GIS Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAR file extension

Java Archive File

Executable Files

KMZ file extension

Google Earth Placemark File

GIS Files

M file extension

Objective-C Implementation File

Developer Files

MSG file extension

Outlook Mail Message

Text Files

3DM file extension

Rhino 3D Model

3D Image Files