A wiki (IPA: [ˈwɪ.kiː] or [ˈwiː.kiː]Ώ]) is a website that allows visitors to add, remove, edit and change content, typically without the need for registration. It also allows for linking among any number of pages. This ease of interaction and operation makes a wiki an effective tool for mass collaborative authoring. The term wiki can also refer to the collaborative software itself (wiki engine) that facilitates the operation of such a site, or to specific wiki sites, including the computer science site WikiWikiWeb (the original wiki) and online encyclopedias such as Wikipedia.