the earths magnetic field

The Earth does not contain a giant bar magnet, but it behaves as if it does. The Earth has a magnetic pole in the north and one in the south. Compasses work because bar magnets can line up in the Earth's magnetic field and point north. Make sure you understand these things:
the north pole of a bar magnet is actually called the 'north-seeking pole', and it points to the Earth's magnetic pole in the northern hemisphere
the south pole of a bar magnet is actually called the 'south-seeking pole', and it points to the Earth's magnetic pole in the southern hemisphere. The magnetic pole near the geographical North Pole attracts a bar magnet's north pole because it is in fact a magnetic south pole. In geography and navigation it is always called the 'north magnetic pole' which can make things confusing.

Small compasses called plotting compasses can be used to show the magnetic field around a bar magnet, instead of using iron filings. The needle in each compass turns and lines up along the field lines.

f we arrange some plotting compasses around a bar magnet, we see that the needles point away from the magnet's north pole and towards its south pole.