Maritime transport involves the shipment of cargo and passengers via waterways using various types of vessels. Historically, general cargo ships transported a variety of goods but have been largely replaced by bulk carriers, container ships, and roll-on/roll-off vessels optimized for certain cargo types. Modern ships come in many designs like bulk carriers for commodities, tankers for liquids, gas carriers for liquefied cargoes, container ships and roll-on/roll-off ferries for wheeled cargo, and passenger vessels for transporting people. Efficient maritime transport is important for global trade and economic development.