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

GPX file extension

GPS Exchange File

GIS Files

HTML file extension

Hypertext Markup Language File

Web Files

JPG file extension

JPEG Image

Raster Image Files

M file extension

Objective-C Implementation File

Developer Files

M3U file extension

Media Playlist File

Audio Files

MP4 file extension

MPEG-4 Video File

Video Files

PIF file extension

Program Information File

Executable Files

PPT file extension

PowerPoint Presentation

Data Files

RM file extension

Real Media File

Video Files

RSS file extension

Rich Site Summary

Web Files

SITX file extension

StuffIt X Archive

Compressed Files

SWF file extension

Shockwave Flash Movie

Video Files

TTF file extension

TrueType Font

Font Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

YUV file extension

YUV Encoded Image File

Raster Image Files