It runs on MediaWiki, a software solution maintained by the Foundation.
MediaWiki admits extensions, such as Wikibase. Wikibase transfers the classic wiki principles (usually applied to curating wikitext) into curating a semantic knowledge base. Wikibase thus allows maintaining a semantic web knowledge base in a collaborative way. The most well known instance of the Wikibase software is Wikidata, also a project of the Wikimedia Foundation.