Wikipedia (/ˌwɪkɪˈpiːdiə/ (listen) wik-ih-PEE-dee-ə or /ˌwɪkiˈpiːdiə/ (listen) wik-ee-PEE-dee-ə; abbreviated as WP) is a multilingual online encyclopedia created and maintained as an open collaboration project by a community of volunteer editors using a wiki-based editing system. It is the largest and most popular general reference work on the World Wide Web. It is also one of the 20 most popular websites ranked by Alexa, as of March 2020[update]. It features exclusively free content and no commercial ads and is owned and supported by the Wikimedia Foundation, a non-profit organization funded primarily through donations.