what3words has divided the entire world into 3m squares and given each square a unique identifier made from three words. The words are distributed by a mathematical algorithm; they are fixed and will never change. what3words addresses are accurate to 3m x 3m, enabling them to specify a precise entrance, unlike a street address which identifies an entire building.

We chose 3 metres x 3 metres as it is small enough to be useful for labelling specific areas, such as a water point or a front gate, but not so small that we run out of words to label all the squares, or have the squares so small that they become too specific for locations such as houses.