When looking forward towards the bow of a boat, the right-hand side is called the starboard side, while the left-hand side is called the port side. The reason for using these terms instead of "left" and "right" is that port and starboard never change, so they are unambiguous references that are independent of a mariners orientation. In the early days of boating, before ships had rudders on their centerlines, boats were controlled using a steering oar. Most sailors were right-handed, so the steering oar was placed over or through the right side of the stern. Sailors began calling the right side the steering side, which soon became "starboard" by combining two Old English words: stéor (meaning "steer") and bord (meaning "the side of a boat") . As the size of boats grew, so did the steering oar, making it much easier to tie a boat up to a dock on the side opposite the oar. This side became known as larboard, or "the loading side." Over time, larboard was replaced with port, as it was too easily confused with starboard.

There are several ways to remember which side is starboard and which is port. One way is to remember that "right" and "starboard" both have the letter "R" in them. Another way is to remember that the word "port" has four letters, just like the word "left". Additionally, the port side of a boat is where the red navigation light is located, while the starboard side has a green navigation light. Knowing which side is which is important for communication and safety reasons while boating.