The world's biggest magnet
The biggest magnet on the planet is the earth itself. The earth consists of a relatively shallow crust atop a thick, rocky mantle. Under the mantle is a dense core of liquid metal (mostly iron) surrounding a solid-metal center.
Scientists think the movement of electrical charges in the earth's outer core creates the earth's magnetic field. Like every magnet, the earth has a north pole and a south pole. The magnetic poles are close to what we call the North and South poles.
Compass needles are magnets, too, with a north and south pole. And when a compass points north, it's actually the north pole of the compass needle that's being attracted to the south magnetic pole of the earth ... which happens to be near the North Pole.
Confused? Don't be. Just be grateful the earth's magnetic field isn't a lot stronger than it is, because how would you like it if your steel-framed bike took off by itself to the North Pole?