A grid reference indicates a location on a map in terms of numbered vertical and horizontal grid lines. Grid references are useful for sharing routes, and quickly communicating to emergency services. Bushwalkers often share grid references of campsites or camp caves, obstacles or challenges on a walk, where to get through a cliff line, where to cross a river or what route to take. Orienteering competitions also provide information on their flag locations using grid coordinates.

To share a grid reference, the name of the map must be given, plus the X and Y coordinates. Users must also be clear on the reference system used.