Wiki definition

According to Wikipedia, Wiki is the world's largest site.

A Wiki ([ˈwiː.kiː] <wee-kee> or [ˈwɪ.kiː] <wick-ey>) is a type of website that allows users to add, remove, or otherwise edit and change most content very easily.

And that is it! As a part of wikidot.com network this site is a customizable piece of the Internet where users can edit content, upload files, communicate and collaborate.