Magnetic North refers to the north indicated by a compass. Since the Earth's magnetic poles do not align with the geographic north and south poles, the north indicated by a compass is magnetic north rather than true north. Magnetic north shifts over time, a phenomenon known as 'Chandler Wobble'.

True north is the starting point for all meridians on maps or globes, also known as the geographic North Pole. The difference between true north and grid north is minimal and can be ignored for navigation purposes.

Grid north refers to any arbitrarily defined reference direction in rectangular coordinates overlaid on nautical charts. It is the 'up' direction indicated by the vertical grid lines on a specific map and is primarily used in engineering surveys.