What are the ends of a magnet called?

The ends of a magnet are called the poles. Each magnet has a north pole and south pole. Magnetic fields have field lines, which begin at the north pole of a magnet and end at the south pole.

The north pole of one magnet and the south pole of another magnet, however, attract one another. Each single magnet must have a north pole and a south pole to be a magnet. Even when a magnet is broken, each piece contains its own north and south poles. The north poles of two magnets repel each other; conversely, the south poles of two magnets placed end to end repel each other.

Earth can be likened to a large magnet; the field lines of Earth's magnetic field are generated at its North Pole and ends at its South Pole.