True North: The plane passing through the height of the observer's eyes and perpendicular to the vertical line of the observer. It is called the true ground plane of the observer's ground, and the meridian circle passing through the observer is called the observer's meridian circle. The plane containing the meridian circle is called the meridional plane. The intersection of the surveyor's meridian and the surveyor's true ground plane points in the direction of the geographical North Pole. North defined in this way is also called true north. Magnetic North: When affected only by the geomagnetic field, the projection of the o-degree direction of the magnetic compass on the true ground plane is called magnetic north. The angle between true north and magnetic north is called magnetic variation. When the magnetic north line deviates to the east of true north, it is called eastward magnetic variation. Use the "+" sign when calculating; the magnetic north line deviates from the true north line by one unit, which is called the magnetic deviation to the west, and use the "one" sign when calculating. Coordinate north, also called map north and grid north, refers to the "upper" direction indicated by the vertical grid lines on a map. That is the so-called up north and down south.
The three do not overlap. Sometimes the grid north and the true north coincide, and sometimes they do not. This depends on the projection system and coordinate system selected when drawing.