Masts are tall, vertical structures used in sailing and other maritime activities. The term 'masts' can refer to two different types of structures: SPARS and poles. SPARS are long, thin pieces of wood or metal that are used to support sails and rigging. Poles are thicker, sturdier structures that are used to support masts and other structures on a ship. Both SPARS and poles are essential components of a sailing vessel.