How do asteroids end up in the asteroid belt instead of becoming a planet?

The asteroid belt between Mars and Jupiter contains millions of rocky objects, but the total mass is only a tiny fraction of Earth’s Moon. In the early Solar System, material in that region never accreted into a planet because Jupiter’s strong gravity stirred up collisions and disrupted growth. The belt is therefore a collection of remnants from planetary formation rather than a shattered planet. Objects there range from dust to dwarf-planet-sized bodies like Ceres. Studying asteroids helps scientists understand the building blocks of the planets.