I've seen fewer and fewer chefs wearing the traditional chef's hat (toque blanche). I still had to wonder why anyone started wearing it at all. I found the answer on Chef Talk. During the 16th century, "artisans of all types (including chefs) were often imprisoned, or even executed, because of their freethinking. To alleviate persecution, some chefs sought refuge in the Orthodox Church and hid amongst the priests of the monasteries. There they wore the same clothes as the priests-including their tall hats and long robes." At that time, however, the chefs' clothes were gray.
In the mid 1800's, the uniforms were redesigned by chef Marie-Antoine Carême. He made them white to represent the cleanliness of the kitchen. He also came up with the idea that hat height would represent status in the kitchen. His was said to be 18 inches tall. Chef Talk also explains that "the folded pleats of a toque, which later became an established characteristic of the chef's hat, were first said to have been added to indicate the more than 100 ways in which a chef can cook an egg."For more about the history of the entire chef's uniform, read Jackets and Toques The History of the Chef Uniform on Chef Talk.