On ships, the directions "right" and "left" are not commonly used, and mariners use nautical terms instead. Starboard is the right-hand side of the ship as seen from someone aboard the ship, facing the bow, or front. Port is the opposite side, or the left side of the ship. One benefit of using these nautical terms is that they do not change depending on which direction a person is facing.
The etymology of the word "starboard" is fairly straightforward. It comes from a combination of two Old English words: stéor, meaning "steer" and bord, meaning "the side of a boat or a ship." The rudder, used to steer a ship, was originally on the right-hand side, and the term stéorbord, "the steering side of a ship," evolved into the term used today.
The opposite side was larboard, or "the loading side." This was too easily confused with its rhyming opposite, so was later changed to port. The term may have come from the fact that cargo was routinely loaded from the port onto the left-hand side, or from the Latin words for harbor or door. "Port" was officially accepted over "larboard" by Britain's Royal Navy in the 1840s.
The starboard side of most ships is usually the "senior" side, with the flag of the captain being raised on this side. On the quarterdeck, this side is generally reserved for the captain, and if the ship carries its own gangway, the officers' gangway is stored on the right as well.
On seagoing vessels, as well as aircraft, the starboard side is designated with a green light, while the port side has a red light. A white light is mounted on the aft or rear side of the ship. This is true of ships around the world.
Many landlubbers have trouble remembering which side of a ship is starboard and which is port. One mnemonic device is to remember that port wine is generally red, so the port side has a red light. Another is to be aware that "left" comes before "right" in the alphabet, and "port" comes before "starboard." "Left" also has four letters, so it must match with the other four-letter word, "port." Of course, all these clues only work when a person is facing the front of a ship.
