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

AI file extension

Adobe Illustrator File

Vector Image Files

AVI file extension

Audio Video Interleave File

Video Files

CFG file extension

Configuration File

Settings Files

CSS file extension

Cascading Style Sheet

Web Files

DRV file extension

Device Driver

System Files

ICS file extension

iCalendar File

Misc Files

JS file extension

JavaScript File

Web Files

JSP file extension

Java Server Page

Web Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

M4A file extension

MPEG-4 Audio File

Audio Files

MDF file extension

Media Disc Image File

Disk Image Files

SQL file extension

Structured Query Language Data File

Database Files

TORRENT file extension

BitTorrent File

Misc Files

VCF file extension

vCard File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files