geohash
Simple implementation of GeoHash algorithm for tech talk.
Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer[1], which encodes a geographic location into a short string of letters and digits. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order curve, and generally space-filling curves.
from Wikipedia