The ruled squares over a map, from which a position is quoted as a grid reference.
Also known as: National grid square, Blue squares on a map, Map grid
The blue grid over a map is a coordinate system, not a feature of the ground. A grid reference names a square rather than a point, and how many digits are quoted decides how small that square is.
Divides the map into squares of a fixed ground size, from which a position is quoted as a grid reference.
United Kingdom · Contexts: Navigation, Maps
Names a square rather than a point: a six-figure reference identifies a hundred-metre square and an eight-figure one a ten-metre square.
United Kingdom · Contexts: Navigation, Maps
Is aligned to grid north, which differs slightly from true north and from magnetic north — a difference the map's margin states.
United Kingdom · Contexts: Navigation, Maps
Thin straight lines, usually blue, ruled across the map at even spacing in two perpendicular directions, with numbers printed along the margins.
The grid is aligned to grid north, which the arrow distinguishes from true and magnetic north.