Conventional compasses align themselves with the Earth's magnetic field at a given location.
If one were to follow the indications of a magnetic compass until he reached either of the magnetic poles, north or south, his path would not be the most direct possible. It would be a somewhat irregular course which would, true enough, end at the magnetic pole, but would certainly not represent the course a navigator would plot. Magnetic north and south, in other words, are simply the direction indicated by a compass needle when it is aligned with the magnetic lines of force at any given location. The magnetic lines of force of the Earth are not straight, like the artificial meridians on a globe. The magnetic poles might be described as simply the places where the Earth's magnetic lines of force all come together after their more or less wandering journey and, in a sense, dive beneath the ground.