Why do ships have sails?

Answer 1

Ships have sails to catch the wind and propel them through the water. Some modern vessels have sails out of nostalgia for the older sailing methods, while the actual historical vessels had no engines and, therefore, depended on the wind to carry them. They are testing a type of sail that looks more like a large kite or parasail. They are to be used by large ships to help lessen their fuel consumption. It has been tested on Super tankers