Applications of polarimetric synthetic aperture radar (SAR) for earth sensing and monitoring flourished in the last two decades due to the abundant availability of airborne and space-borne PolSAR data. We have discussed PolSAR techniques for terrain and forest classifications in Chapters 8 and 9 respectively. PolSAR information extraction algorithms have also been developed for other applications such as biomass and forest height estimation, snow wetness and thickness measurement, snow cover mapping, surface geophysical parameters estimation (soil moisture and surface roughness), glacier monitoring and measurement, hazard monitoring and damage assessment (earthquake, landslide, flood, forest fire, etc.), ocean wave, current and surfactant sensing, wetland preservation, deforestation monitoring, etc. They are too numerous to be included in this book. In this chapter, several applications are selected to further demonstrate the superior capability of PolSAR compared with single polarization SAR and optical sensors.