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

CFG file extension

Configuration File

Settings Files

CLASS file extension

Java Class File

Developer Files

DDS file extension

DirectDraw Surface

Raster Image Files

DMP file extension

Windows Memory Dump

System 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

FLV file extension

Flash Video File

Video Files

GPX file extension

GPS Exchange File

GIS Files

PHP file extension

PHP Source Code File

Web Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

3DS file extension

3D Studio Scene

3D Image Files