To correct magnetic declination, you’ll need to know ... Some compasses allow you to set the declination adjustment so that the compass automatically accounts for the angle.

and place your compass on the map as before after adjusting for declination (see below). The difference between True North (toward the North Pole, and usually the top of a map) and Magnetic North ...

This reliance on the earth's magnetic field does ... should look for when choosing a compass (beyond the essential components) include a declination adjustment, sighting mirror, clinometer ...