Navigation

North	True North	Is the North that is the actual "real" North, it is the top of the North / South axis around which the earth rotates. It is the North pole. However it is not used in navigation as grid North is much easier to use.
or North	Grid North	Is the northerly direction of the North-South grid lines on a map. The Grid starts at Greenwich, and uses lines of Longitude and Latitude. It is then sub devised into smaller areas (as used by the national grid.)
or North	Magnetic North	Is the North that the red end of the compass point is attracted to, and is therefore used for direction finding. It is a magnetic field in the earth’s crust that can reliably used for navigation. As we can calculate exactly where this North is, we can also calculate the difference between this and Grid North thus allowing us to determine correct direction of travel. Remember ~ The Magnetic North varies in different parts of the world
Gives you North	Magnetic Variation	There is the difference between magnetic north and grid north, because of this difference, we use a "Magnetic variation" when working from one to the other. This variation is found in the margin information of the map, it varies according to how far East or West you are, and alters with time. When transferring from map to the field this variation must be added, (and vice versa.)