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

BAK file extension

Backup File

Backup Files

CUR file extension

Windows Cursor

System Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DRV file extension

Device Driver

System Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GADGET file extension

Windows Gadget

Executable Files

MDF file extension

Media Disc Image File

Disk Image Files

MP3 file extension

MP3 Audio File

Audio Files

MSI file extension

Windows Installer Package

Misc Files

PAGES file extension

Pages Document

Text Files

PHP file extension

PHP Source Code File

Web Files

TTF file extension

TrueType Font

Font Files

VCD file extension

Virtual CD

Disk Image Files

VCF file extension

vCard File

Data Files

3G2 file extension

3GPP2 Multimedia File

Video Files