Geocode

A geocode is a code that represents a geographic entity (location or object). It is a unique identifier of the entity, to distinguish it from others in a finite set of geographic entities. In general the geocode is a human-readable and short identifier.

Typical geocodes (in bold) and entities represented by it:

• Country code and subdivision code. Polygon of the administrative boundaries of a country or a subdivision.
  The main examples are ISO codes: ISO 3166-1 alpha-2 code (e.g. AF for Afghanistan or BR for Brazil), and its subdivision conventions, such as AF subdivision codes (e.g. AF-GHO for Ghor province) or BR subdivision codes (e.g. BR-AM for Amazonas state).

• DGG cell ID. Identifier of a cell of a discrete global grid: a Geohash code (e.g. ~0.023 km² cell 6vd23gq at Brazil's centroid) or a Plus Code (e.g. ~0.0002 km² cell 58Q8XXXX+XX within the same area).

• Postal code. Polygon of a postal area: a CEP code (e.g. 70040 represents a Brazilian's central area for postal distribution).

The ISO 19112:2019 standard (section 3.1.2) adopted the term "geographic identifier" instead geocode, to encompass long labels: spatial reference in the form of a label or code that identifies a location. For example, for ISO, the country name “People's Republic of China” is a label. Some authors, such as the United States Census Bureau, use the abbreviation "GEOID" as a synonym for geocode.

Geocodes are mainly used (in general as an atomic data type) for labelling, data integrity, geotagging and spatial indexing.

In theoretical computer science a geocode system is a locality-preserving hashing function.