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

COM file extension

DOS Command File

Executable Files

CRX file extension

Chrome Extension

Plugin Files

CUR file extension

Windows Cursor

System Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FLA file extension

Adobe Flash Animation

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

JPG file extension

JPEG Image

Raster Image Files

MP4 file extension

MPEG-4 Video File

Video Files

PIF file extension

Program Information File

Executable Files

PNG file extension

Portable Network Graphic

Raster Image Files

PPS file extension

PowerPoint Slide Show

Data Files

SLN file extension

Visual Studio Solution File

Developer Files

YUV file extension

YUV Encoded Image File

Raster Image Files

3DS file extension

3D Studio Scene

3D Image Files