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

ASPX file extension

Active Server Page Extended File

Web Files

BIN file extension

Binary Disc Image

Disk Image Files

CPL file extension

Windows Control Panel Item

System Files

DAT file extension

Data File

Data Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DOC# file extension

Microsoft Word Document

Text Files

JPG file extension

JPEG Image

Raster Image Files

KEY file extension

Keynote Presentation

Data Files

MID file extension

MIDI File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

NES file extension

Nintendo (NES) ROM File

Game Files

PPT file extension

PowerPoint Presentation

Data Files

PRF file extension

Outlook Profile File

Settings Files

SAV file extension

Saved Game

Game Files

VCF file extension

vCard File

Data Files