What is difference between a suit and a shirt?

Well, I did some quick research, and found that a suit is not only just the part you wear over your body, but it also includes the tie and the trousers and stuff. A shirt you just wear over the torso and it. . . is less formal, I guess. You can go here for more information. : http://en.wikipedia.org/wiki/Suit : http://en.wikipedia.org/wiki/Shirt