SRID
A numeric identifier for a coordinate reference system used by some databases and formats (especially PostGIS and EWKB).
Category: CRS & Coordinates
Definition (expanded)
SRID connects a geometry to a CRS (e.g., 4326). GeoJSON typically does not include SRID. EWKB can embed SRID so databases can enforce consistency and run correct measurements and transforms.
Related terms
CRS (Coordinate Reference System)A definition of how coordinates map to real locations on Earth, including projection, datum, and units.EPSG:4326 (WGS84 lon/lat)A common coordinate reference system using longitude/latitude on WGS84.EWKB (Extended WKB)A PostGIS extension to WKB that can include SRID and additional flags.EWKT (Extended WKT)A PostGIS-style WKT string that can include SRID, like SRID=4326;POLYGON((...)).