Where do the terms “port” and “starboard” come from?

Before ships had rudders on their centerlines, they were steered using a specialized oar held by an oarsman located in the stern (back) of the ship. Since there were many more right-handed sailors than left-handed, the oar was affixed to the right side of the ship. The word starboard comes from the Old English word steorbord, literally meaning the side on which the ship is steered.  The term for the left side of the boat, larboard, is derived from the practice of sailors mooring on the left side (i.e., the larboard or loading side) to prevent the steering boards from being crushed. As "larboard" and "starboard" sounded too similar, larboard was changed to port.