Why use circular polarization?

In a circularly polarized antenna places equal energy in both horizontal and vertical planes.  Since the tip of the electric field vectors rotate in a corkscrew fashion as it propagates, energy is not only in the Horizontal and Vertical planes but all planes in between.  This immensely helps in receiving a usable signal in adverse propagation conditions such as Reflectivity, Absorption, Phasing Issues and Multi-path.  Popular use cases for this polarization are RFID and Satellite communications.