The Van Allen Radiation Belts are trapped in the Earth's geomagnetic fields. There are two belts which are toroidal (shaped like donuts or bagels) with Earth at the center. Both belts, an inner belt and an outer belt, are composed of plasma (highly energetic charged particles such as electrons and protons).
The Van Allen belts are oddly shaped toroids, however, because
their shape is distorted by the "Solar Wind" of particles streaming
from the Sun. The Earth, rotating at the center of the toroids, is
roughly 8,000 miles (13,000 km) wide and nearly circular. The
outer Van Allen belt extends roughly 8,000 miles (13,000 km) into
space on the sunny side of the Earth and roughly 56,000 miles
(91,000 km) into space on the dark side. The inner belt extends
roughly 1/2 the distances of the outer belt.