Open data, this new subject of overall attention, that some don't hesitate to picture as the “black gold” of modern times, quickly became one of the major concerns of humanity, which no one can take lightly nor to ignore. Nowadays, one tries to pay more attention to this new societal, cultural and economical paradigm, in order to better apprehend its complexity as well as measuring the impact it may have or has already, on our societies. This study offers an update of the Open data movement and on the open data themselves. It especially introduces the key topics (at legal, technical, and economic levels) to anyone who wants to get into the Open data venture in order to better assess its nature and its various facets.