The asteroid belt is a region in space located between the orbits of Mars and Jupiter. It contains a vast number of rocky objects, known as asteroids, which vary in size from small boulders to large bodies hundreds of kilometers wide. These asteroids are remnants from the early solar system that never coalesced into a planet. The total mass of the asteroid belt is much less than that of Earth's Moon, and it is estimated to contain millions of asteroids. Some of the most well-known asteroids include Ceres, which is classified as a dwarf planet, and Vesta, one of the largest asteroids in the belt.