GeoJSON Geographic data format

It is a standard for representing vector data in JSON format (plain text). 

The Geography data type and its specific data types (GeoPoint, GeoLine, and GeoPolygon) can use the FromGeoJSON method to load the vector data from its representation in GeoJSON format.

Similarly, the ToGeoJSON method allows you to obtain the vector data's representation in GeoJSON format.

See Also

Geography data type
https://en.wikipedia.org/wiki/GeoJSON