What is a wiki

From Wikipedia

A wiki is a collection of interlinked web pages, each of which can be visited and edited by anyone. You can even edit this page: just click "Edit text of this page" below!

This is a collaborative website, constantly expanding as new people add pages about their interests, comment on old pages, et cetera.

Perhaps you would also like to know the answers to the following questions.

What is a Wiki for?
Why on Earth would I want to contribute to a wiki?
Who is responsible for these pages?
How does one start a page?
How does one edit a page?
Just why is Wikipedia so great, anyway?
How can I build a Wiki of my own?