Port and starboard are nautical terms which refer to the left and right sides, respectively, of a ship as perceived by a person on board facing the bow (front of the ship). In lay terms, when observing the bow from the bridge of a watercraft, port refers to the left side of the ship and starboard refers to the right. An easy way to remember this is that port and left are both four-letter words, which only leaves starboard as the opposite side. At night, the port side of a vessel is indicated with a red navigation light and the starboard side with a green one. These terms can also be applied to aircraft, particularly to airships in naval use, and eventually for all forms of heavier-than-air aircraft, particularly for the waterborne seaplane, existing in both floatplane and especially for flying boats of both civilian and military types, with aircraft of all types even adopting similar navigation lights to those of boats and ships. The starboard side of most naval vessels the world over is designated the “senior” side. The officers’ gangway or sea ladder is shipped on this side and this side of the quarterdeck is reserved for the captain. The flag or pennant of the ship’s captain or senior officer in command is generally hoisted on the starboard yard.