Don't worry if the futures market for commodities seems confusing. There are better ways to invest in commodities then playing the futures market directly. In fact, unless you are a very sophisticated (and most likely professional) investor, the futures market is best left alone.
Did you know that oil is the most traded commodity? It makes sense since we use oil for so many things: gas, heating fuel, plastics. Humans will probably always require energy in some form. Oil just happens to be the "king" right now.