A mast is a tall spar or arrangement of spars erected vertically on the center-line of a ship or boat. Its purposes include carrying sails, spars, and derricks, giving necessary height to a navigation light, look-out position, signal yard, control position, radio aerial, or signal lamp. Large ships have several masts, with the size and configuration depending on the style of the ship. Until the mid-19th century, all vessels masts were made of wood formed from a single or several pieces of timber, which typically consisted of the trunk of a conifer tree. From the 16th century, vessels were often built of a size requiring masts taller and thicker than from single tree trunks. On these larger vessels, to achieve the required height, the masts were built from up to four sections (also called masts) .
In addition to its nautical meaning, "mast" can also refer to a slender vertical or nearly vertical structure, such as an upright post in various cranes. It can also refer to a disciplinary proceeding at which the commanding officer of a naval unit hears and disposes of cases against enlisted men, also called captain's mast. Finally, "mast" can also be used as a verb, meaning to furnish with a mast.
