A wiki ( ) is a website which allows collaborative modification of its content and structure directly from the web browser. In a typical wiki, text is written using a simplified markup language (known as "wiki markup"), and often edited with the help of a rich-text editor.

A wiki (or wiki wiki) is a collaborative website. Wiki or wiki wiki may also refer to the following:

• WikiWikiWeb, the original wiki website, and originator of the word "wiki"
• Wiki software, software used to run a wiki website
• Wikipedia, a wiki encyclopedia sometimes referred to as "wiki"
• .wiki, a generic top-level domain overseen by ICANN.