The cowboy hat is the defining piece of attire for the North American cowboy without doubt. When a child sees someone with one, they think, and often say, "cowboy!" They can be defined as a wide brimmed hat with a high crown, but everyone knows one when they see one. Actually, the traditional of wearing similar hats goes all the way back to Mongolian horsemen in the 13th century. It is not an American invention.
Cowboy hats are made of felt commonly, but straw and leather are also common today. They normally have a small band inside to help hold them on the head and a decorative headband on the outside. They come in all colors, but brown, black, and beige are most common. In Western movies, the bad guys wore black hats and the good guys wore white hats. Even today, the term "black hat" refers to someone engaged in unethical or illegal activity and "black hat" refers to someone engaged in purely legitimate activity, with "gray hats" coming somewhere in between.