The asteroid belt is a region in the solar system located between the orbits of Mars and Jupiter. It is a torus-shaped ring made up of numerous irregularly shaped rocky bodies called asteroids or minor planets. These asteroids vary in size from small rocks to objects hundreds of kilometers in diameter, with the largest being dwarf planet Ceres. The belt's mass is relatively small, containing only about 3% of the Moon's mass, and its asteroids are spaced far apart, meaning spacecraft can safely pass through it. The asteroid belt exists because, during the early formation of the solar system, the strong gravitational influence of Jupiter prevented the material in this region from coalescing into a full planet. Instead, the material collided and broke into smaller bodies that formed the belt we see today. This gravitational interference from Jupiter essentially halted planet formation here and created a stable zone where these many smaller bodies orbit the Sun without forming a larger planet. In summary, the asteroid belt is a collection of leftover building blocks of the solar system that never formed into a planet due to Jupiter's powerful gravity, resulting in a distinct ring of rocky bodies between Mars and Jupiter.