What are coordinates?

Coordinates are numerical values fixing a position on Earth or in a projection. Most common: longitude and latitude (WGS84, EPSG:4326) or X/Y in a projected system such as RD New (EPSG:28992) in the Netherlands.

Without the correct coordinate reference system (CRS), distances, overlays, and links fail. PDOK services and BAG deliver data in defined CRS; web maps often display WGS84 or Web Mercator.

Coordinates are not an address (a semantic label) or full geometry — a point has one coordinate pair; lines and polygons have coordinate sequences. Geocoding links addresses to coordinates.