Port is the nautical term (used on boats and ships) that refers to the left side of a ship, as perceived by a person on board the ship and facing towards the bow (the front of the vessel). The terms are also used for aircraft, spacecraft, and analogous vessels. The equivalent for the right-hand side is starboard.
An archaic version of the term is larboard. The term larboard, when shouted in the wind, was presumably too easy to confuse with starboard and so the word port came to replace it, referring to the side of the ship where cargo is loaded from the port. The term larboard continued its use well into the 1850s by whalers, despite the term being long superseded by "port" in the merchant vessel service at the time. The term was not officially adopted by the Royal Navy until 1844 (Ray Parkin, H. M. Bark Endeavour). Robert FitzRoy, Captain of Darwin's HMS Beagle, is said to have taught his crew to use the term port instead of larboard, thus propelling the use of the word into the Naval Services vocabulary. Another source suggests a different archaic word "portboard" (see the starboard article for further explanation).
The word starboard comes from Old English steorbord, literally meaning the side on which the ship is steered. The old English term stēorbord descends from the Old Norse words stýri meaning “rudder” (from the verb stýra, literally “being at the helm”, “having a hand in”) and borð meaning etymologically “board”, then the “side of a ship”.
In many languages, other than English, the word is derived from a Germanic term akin to "backboard", from the same roots as English "back" and "board".
A port buoy is a lateral buoy used to guide vessels through channels or close to shallow water. The port buoy is one that a vessel must leave to port when passing upstream. If in IALA area A, the port buoys are red. If in IALA area B (Japan, the Americas, South Korea, and the Philippines) then the 'handedness' of buoyage is reversed, and black or green buoys are left to port.
Ships and aircraft carry a red light on the port side, and a green one on the starboard side, plus a white light at the rear.
There are a number of tricks used to remember port and starboard:
Port, the drink, is a fortified red wine which links the word port with the colour red, used for the navigation lights (see below). "left" comes from the phrase and so port must be on the left. The reference to "can" relates to the fact that port-hand harbour buoys are "can" shaped (only in IALA region A)
For buoys in IALA B: