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

ACCDB file extension

Access 2007 Database File

Database Files

DEM file extension

Video Game Demo File

Game Files

DTD file extension

Document Type Definition File

Developer Files

FLA file extension

Adobe Flash Animation

Developer Files

H file extension

C/C++/Objective-C Header File

Developer Files

JS file extension

JavaScript File

Web Files

MDB file extension

Microsoft Access Database

Database Files

MP3 file extension

MP3 Audio File

Audio Files

RA file extension

Real Audio File

Audio Files

SWF file extension

Shockwave Flash Movie

Video Files

TOAST file extension

Toast Disc Image

Disk Image Files

TTF file extension

TrueType Font

Font Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

YUV file extension

YUV Encoded Image File

Raster Image Files