The formats were originally defined by the Open Geospatial Consortium (OGC) and described in their Simple Feature Access.
[2] WKT can represent the following distinct geometric objects: Coordinates for geometries may be 2D (x, y), 3D (x, y, z), 4D (x, y, z, m) with an m value that is part of a linear referencing system or 2D with an m value (x, y, m).
For example, PostGIS contains functions that can convert geometries to and from a WKT representation, making them human readable.
It also states that if the exterior linear ring of a polygon is defined in a counterclockwise direction, then it will be seen from the "top".
[3] The following are some other examples of geometric WKT strings: (Note: Each item below is an individual geometry.)