These are the main themes introduced and explored by artists that, between the late 50s and the early 70s, founded a real international movement, mainly represented by Group Zero (founded in Dusseldorf in 1958, from the vision of Heinz Mack, Otto Piene, Günter Uecker), New Tendencies (started in Zagreb in 1961), and other important work centers and research groups across Europe, which not only reached the Netherlands, Germany, Belgium, France, Switzerland and Italy, but also the United States and Japan.