Magnetosphere refers to that area of space around a planet that is controlled by that planet's magnetic field. It protects the Earth from certain types of radiation from the Sun. The inner magnetosphere is the region of magnetosphere that contains the plasmasphere, ring current, and the radiation belts all co-located within about 6.6 times of the Earth's radius. These belts are highly dynamic, increasing, and decreasing on time scales of minutes to years. A radiation belt refers to the zone of energetic charged particles that generally originates from the solar wind that is captured by and held around a planet by that planet's magnetosphere. Radiation belts are regions of enhanced populations of energetic electrons and protons surrounding the Earth in space. There are two radiation belts of Earth, the inner radiation belt and the outer radiation belt. This book outlines the dynamics of the Earth's radiation belts and inner magnetosphere in detail. It is a resource guide for experts as well as students.