Why does a compass point north?
The short answer
A compass needle turns to align with Earth's magnetic field and points roughly toward magnetic north.
How it works
One end of the needle acts like a magnetic pole. It settles along the local field. Magnetic north is not exactly the same as the geographic North Pole and changes slowly with location and time.
A familiar example
A phone compass can be disturbed near buildings or wires because nearby materials create extra magnetic fields.