This movie works on so many levels. First there is not one bad or boring scene in it. It hooks the viewer from the beginning. Second you have to appreciate the history behind the film, and admire the fact that some of the lines were written an hour before they aired and they are still quoted today. Finally you have to understand and appreciate the time the film came out right during World War II. For Warner Brothers this was just another movie, they had no idea the impact it would make. So why is this such a great movie? It's a story of having loved and lost, of trust and betrayl, of loving two men and doing the honorable thing. The characters are ambigious. There is no true fleshed out hero or villian. It has one of the greatest casts of any film Humphrey Bogart, Ingrid Bergman, Paul Henreid, Claude Rains, Conrad Veidt, Dooley Wilson, S.Z Sakall, Sydney Greenstreet, and Peter Lorre. They each give a memorable performance. Once you watch Casablanca you don't forget it.