North is one of the four cardinal directions. In European and American maps, it is generally conceived of as the top or upward direction, whereas South is directed towards the bottom.
In medieval European mythology, north is the direction of Hell.
Magnetic vs. true
True north (the north pole) is a set location, which appears on earth to stand just below the north star. However, the earth's magnetic field fluctuates, so magnetic north does not perfectly align with true north. This is believed to be at least partly due to variations in a large underground "river" of molten iron.
Additionally, there is evidence that the earth's magnetic poles have reversed at least once, and possibly more than that. These reversals are rare and catastrophic. Scientists suspect that as a reversal approaches, magnetic and true north increasingly separate, until a complete reversal closely aligns true and magnetic poles (leaving what is known as magnetic north at true south).