A wiki enables documents to be written collaboratively, in a simple markup language using a web browser. A single page in a wiki is referred to as a "wiki page", while the entire body of pages, which are usually highly interconnected via hyperlinks, is "the wiki". A wiki is essentially a database for creating, browsing and searching information.

A defining characteristic of wiki technology is the ease with which pages can be created and updated. Generally, there is no review before modifications are accepted. Many wikis are open to the general public without the need to register any user account. Sometimes session log-in is requested to acquire a "wiki-signature" cookie for autosigning edits. Many edits, however, can be made in real-time, and appear almost instantaneously online. This can lead to abuse of the system. Private wiki servers require user authentication to edit, sometimes even to read pages.