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

CAB file extension

Windows Cabinet File

System Files

CFM file extension

ColdFusion Markup File

Web Files

DEM file extension

Video Game Demo File

Game Files

DOC# file extension

Microsoft Word Document

Text Files

GED file extension

GEDCOM Genealogy Data File

Data Files

GZ file extension

Gnu Zipped Archive

Compressed Files

M4A file extension

MPEG-4 Audio File

Audio Files

MAX file extension

3ds Max Scene File

3D Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MSI file extension

Windows Installer Package

Misc Files

THM file extension

Thumbnail Image File

Raster Image Files

VB file extension

VBScript File

Executable Files

WAV file extension

WAVE Audio File

Audio Files

XML file extension

XML File

Data Files

3GP file extension

3GPP Multimedia File

Video Files