Bolt heads come in various types, each suited for a specific use. Hex head bolts, the most common, offer a balance of torque and accessibility. Square heads provide a large bearing area, ideal for high-torque applications. Carriage bolts are used in wood applications due to their firm hold. Flange bolts have a built-in washer, distributing load and saving time. T-bolts are great for a smooth finish, while eye bolts enable lifting or moving objects. U-bolts support pipework, and Allen or socket head bolts allow for high torque without damaging the bolt head.