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

DRV file extension

Device Driver
System Files

FON file extension

Generic Font File
Font Files

GIF file extension

Graphical Interchange Format File
Raster Image Files

IBOOKS file extension

Multi-Touch iBook
Data Files

INI file extension

Windows Initialization File
Settings Files

KEYCHAIN file extension

Mac OS X Keychain File
Data Files

M4V file extension

iTunes Video File
Video Files

MAX file extension

3ds Max Scene File
3D Image Files

PART file extension

Partially Downloaded File
Misc Files

PL file extension

Perl Script
Developer Files

PPS file extension

PowerPoint Slide Show
Data Files

PRF file extension

Outlook Profile File
Settings Files

VB file extension

VBScript File
Executable Files

VCF file extension

vCard File
Data Files