The Prequels are called that because they cronologically come first but were made second making them prequels to the Original Trilogy (OT). They include 1, 2, and 3 and have a very good story that leads perfectly into the OT. They have good characters and a good story and the most epic duel between Anakin and Obi-Wan. At first people didn't like the prequels, but when the sequels came out they made the preqeuls look better. If you decid to watch Star Wars in chronilgial order it will make perfect sense even the the OT came first.
