Why is the left side of a ship called?

1).- When facing forward, the left side of the boat is called 'port" to distinguish and differentiate it from the starboard side of the vessel.

2).- The left side is the port side and the right side is the starboard side.

3).- Portside.

4).- An easy way to remember this, is that "Port" and "Left" have the same number of letters.

5).- When I was very young, I toured an active US Navy ship. In the captain's quarters, his desk had a small, engraved sign facing the visitor's chairs that read, "Port is Left".

See the related Port and Starboard Wikipedia article listed below for more information:
The left side of a boat is called the port. The right side of the boat is called the starboard. The Windows around the boat is called portholes.