WKT

Well-Known Text (WKT) is a text markup language for representing vector geometry objects on maps. It is defined by the Open Geospatial Consortium (OGC) as part of the Simple Features standard and is widely used to encode geometric data in a human readable form that can be parsed by software.

WKT supports geometry types such as POINT, LINESTRING, POLYGON, MULTIPOINT, MULTILINESTRING, MULTIPOLYGON, and GEOMETRYCOLLECTION. The syntax uses the type name followed by coordinates in parentheses; coordinates within a linestring or polygon are separated by commas, and polygons use nested parentheses to denote rings. WKT strings are ASCII and designed to be easy to read and write by both humans and programs.

WKT has variants including the original WKT1 and the newer WKT2 specification, which provides a more formal grammar and, in some implementations, expanded metadata for coordinate reference systems. Some software applies the Extended Well-Known Text (EWKT) extension to attach an SRID prefix, such as SRID=4326;POINT(30 10), though EWKT is not part of the official OGC standard.

Common uses include exchanging geometry values between GIS software and spatial databases. WKT strings are parsed by functions such as ST_GeomFromText or ST_AsText in database systems and are often included in data interchange formats and APIs.

Examples include: POINT (30 10); LINESTRING (30 10, 10 30, 40 40); POLYGON ((30 10, 40 40, 20 40, 10 20, 30 10)). More complex forms include GEOMETRYCOLLECTION (POINT(4 5), LINESTRING(4 6, 7 8)).