A mast is a tall vertical pole on a ship or boat that holds up the sails. On sailing vessels, masts rise high above the deck, sometimes reaching over 100 feet into the air. The famous clipper ships of the 1800s had multiple masts, each supporting different sails that caught the wind and propelled these graceful vessels across the ocean.

The position of masts on a ship had specific names: the foremast stood near the front, the mainmast in the middle, and the mizzenmast at the rear. Sailors would climb these masts using rope ladders called ratlines, sometimes in storms and rough seas, to adjust the sails. At the top of a mast, a lookout platform called a crow's nest gave sailors a high vantage point to spot land, other ships, or dangerous weather approaching.

Today, even modern sailboats use masts, though they're often made of aluminum or carbon fiber instead of wood. Masts also appear on land: flagpoles are sometimes called masts, and radio towers use tall masts to broadcast signals over long distances.