List of geocoding systems
This is a list of geocoding systems, in the sense of schemes that assign systematic labels to geographic entities.
Some of these code systems are free for use, others have different licences.
Codes with only partial coverture of the globe, mainly for "administrative regions", like countries or biomes.
- ISO 3166-1 and ISO 3166-2: country codes and codes of their subdivisions
- HASC (Hierarchical Administrative Subdivision Codes)
- ONS code, UK only, administrative
- MARC country codes
- SGC codes, Canada only, statistical
- UN M.49 region codes, area code, continents, countries (re-using ISO 3166-1 numeric codes)
- UN/LOCODE, UN codes for trade and transport locations
- IATA airport codes, area /point codes, airports and 3-letter city codes
- ICAO airport codes, area /point codes, airports
Sport codes: IOC country codes, area, worldwide
Environment codes: Longhurst code, a set of four-letter codes used in ecological geography
- U.S., FIPS codes:
- Summarized from Discrete Global Grid
Popular or in "official use":
- ISO 6709 Standard Representation for Geographic Point Location by Coordinates
- Geohash and Geohash-36 open-source hash notation for locations
- Open Location Code (PlusCode)
- What3words, patent-restrictions system, converts 3x3 meter squares into 3 words 
Old or "low use":
- C-squares - compact encoding of geographic coordinate bounds (latitude-longitude)
- World Geographic Reference System (GEOREF), a military / air navigation coordinate system for point and area identification
- Geotude, converts latitude and longitude to a single string
- Global Area Reference System (GARS), reference system developed by the National Geospatial-Intelligence Agency (NGA)
- Military Grid Reference System (MGRS), derived from UTM and UPS grids by NATO with a unique naming convention
- Munich Orientation Convention, converts lat/lon to metrical monopolar codes for targets, crossings, stations, stop points, bridges, tunnels, towns, islands, volcanoes, highway exits etc. 
- S2, a geocoding scheme using spherical geometry and the space-filling Hilbert curve, developed at Google
Telephony & radio broadcasting
- ITU-R country codes
- ITU-T country calling codes
- ITU-T mobile calling codes
- Maidenhead Locator System (used by amateur radio operators)
- Marsden Squares
- Postal codes, area, worldwide, country-codes by UPU, free
- NAC, area codes (area can be indefinitely small)
- NUTS area code, partially administrative, worldwide: countries, Europe : country to community
- OpenPostcode, opensource global algorithm (local adaptations as Irish & Hong Kong postcodes).
- Munich Orientation Convention
Mapping not geodesy
- OpenStreetMap shortlink, used as a short permanent link to map locations
- Quarter Degree Grid Cells
- UN M.49 region codes, area code, continents, countries (like ISO 3166-1 numeric)
- SALB (Second Administrative Level Boundaries), by UN 
- Munich Orientation Convention
- Longhurst code
- "What3words: Find and share very precise locations via Google Maps with just 3 words". Retrieved 8 July 2014.
- By Step Navigation|Navipedia / ESA[permanent dead link]
- "Overview". s2geometry.io. Retrieved 2018-05-11.
- Kreiss, Sven (2016-07-27). "S2 cells and space-filling curves: Keys to building better digital map tools for cities". Medium. Retrieved 2018-05-11.
- "Understanding Geographic Identifiers (GEOIDs)". United States Census Bureau. Retrieved March 3, 2016.
- "OpenPostcode.org". Retrieved 10 June 2012.