Geohash

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. Similar ideas were introduced by G.M. Morton in 1966.^[2] 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.

Geohashes offer properties like arbitrary precision and the possibility of gradually removing characters from the end of the code to reduce its size (and gradually lose precision). Geohashing guarantees that the longer a shared prefix between two geohashes is, the spatially closer they are together. The reverse of this is not guaranteed, as two points can be very close but have a short or no shared prefix.

^
Evidences at the Wayback Machine:
^ G. M. Morton (1966)"A Computer Oriented Geodetic Data Base and a New Technique in File Sequencing" Archived 2019-01-25 at the Wayback Machine. Report in IBM Canada.

[first2008-1] Evidences at the Wayback Machine:
labix.org in 2008, the G. Niemeyer's blog announcing Geohash;

an article about Geohash witnessing and citing G. Niemeyer works, before 2012;

G. Niemeyer's post at forums.geocaching.com announcing Geohash in Feb. 2008.

[2] x.org in 2008, the G. Niemeyer's blog announcing Geohash;

[3] rticle about Geohash witnessing and citing G. Niemeyer works, before 2012;

[4] G. Niemeyer's post at forums.geocaching.com announcing Geohash in Feb. 2008.

[morton66-2] G. M. Morton (1966)"A Computer Oriented Geodetic Data Base and a New Technique in File Sequencing" Archived 2019-01-25 at the Wayback Machine. Report in IBM Canada.

[1]

[2]