In the beginning, Wikipedia was owned by Jimmy Wales. But as it grew, a non-profit charity made more sense, and in 2003 the WMF was established. Today, it owns the trademarks and the servers, develops partnerships and new software, supports local chapters, and runs Wikipedia's annual conference.
In most cases, the Wikimedia Foundation steers clear of getting involved community governance and site content. Its job is simply to help Wikipedia's volunteers do what they do best.