Hull types refer to the different shapes and designs of a boat's hull, which affect its performance, stability, and handling in water. Common hull types include displacement hulls, which move through the water and are ideal for stability, and planing hulls, which rise above the water at speed, allowing for faster travel. Other hull types include catamarans, which have two parallel hulls for increased stability and space, and monohulls, which have a single hull and are popular for their versatility. Each hull type is suited for specific activities, such as fishing, sailing, or recreational boating.