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

PNG file extension

Portable Network Graphic

Raster Image Files

SITX file extension

StuffIt X Archive

Compressed Files

FLA file extension

Adobe Flash Animation

Developer Files

MID file extension

MIDI File

Audio Files

RTF file extension

Rich Text Format File

Text Files

3DM file extension

Rhino 3D Model

3D Image Files

ICNS file extension

Mac OS X Icon Resource File

System Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

M3U file extension

Media Playlist File

Audio Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTML file extension

Hypertext Markup Language File

Web Files

FNT file extension

Windows Font File

Font Files

YUV file extension

YUV Encoded Image File

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files