Hats are a type of HEADGEAR that come in many different styles and materials. MILLINERY is the profession of designing, making, and selling hats. Fedoras are a type of hat with a wide brim and indented crown. LIDS are a slang term for hats. HEADGEAR is a general term for any type of hat or other covering for the head. Caps are a type of hat with a stiff brim and no brim at the back. OPERA hats are a type of formal hat with a low crown and wide brim. Fezzes are a type of hat with a cylindrical shape and flat top. BONNETS are a type of hat with a brim and ties under the chin. SAILORS are a type of hat with a flat top and brim that curves down at the sides. Chapeaux are a type of hat with a wide brim and high crown. Porkpies are a type of hat with a flat top and short brim.