An about page is a meta page on a wiki that describes the wiki, its purpose, its culture (values and norms), and usually its ownership and a little about its history (founding date, etc.) As part of describing the wiki's purpose, the about page will often summarize the wiki's inclusion policy and what the wiki is and what it is not. It may also contain a WikiNode.
By default, MediaWiki links to the wiki's about page from every other page on the wiki (in the footer of the page on most skins). Most wikis also link to it from their main page. WikiIndex's main infobox template for wiki includes the URL of a wiki's about page as a standard parameter. Wikis may encourage new people to read the about page before contributing so that they do not inadvertently violate expectations (e.g. by posting content that is outside the scope of the wiki, or breaching local etiquette when interacting with other contributors).