… Freebase is “open shared database of the world’s knowledge.” This sounds the same as Wikipedia, but it is really quite different, because at the heart of Freebase are the ideas of semantics and openness via API.
Unlike Wikipedia, which is a free form database, Freebase is structured, where concepts and relationships are interlinked into a gigantic network or graph. Another important difference is that Freebase is all about its API. Any information contained inside the database is accessible and can be retrieved via queries. In addition, the data in Freebase is under a Creative Commons license – meaning that is readily exportable and useful by others.