The Magnetic Poles are the points at which the Earth's lines of magnetic force enter and exit the Earth vertically (or straight up and down). At the North Magnetic Pole (NMP) the "dip" (angle towards the Earth) is 90°. The north point of a magnetic compass points to this pole.

This definition was first put forth by Sir William Gilbert (1544-1603), a physician to Queen Elizabeth I. He compared the polarity of a magnet to the polarity of the Earth.

His book, De Magnete ("On the Magnet"), was published in 1600. It was a thorough review of what was known about magnetism at that time, and his magnetic philosophy is still being used today.

Little was known about the lodestone (magnetic iron ore) or magnetized iron. Gilbert was one of the first to research this subject and he added much knowledge through his own experiments.

Europeans were making long voyages across treacherous oceans, and the magnet (as part of a compass pointing to the NMP) was one of the few things that could help keep them from getting fatally lost.

When explorers entered the Arctic, they realized that the NMP was not at the same location as the North Geographic Pole. It then became important to find its exact location, so that the difference between those two poles could be calculated by navigators.