The asteroid belt is located between the planets Mars and Jupiter. It is populated by debris leftover after the planets formed over 4.5 billion years ago.
The debris ranges from the size of a dust particle to the size of a dwarf planet and is sparsely scattered, making collisions between asteroids rare and navigation of the belt easy.
Occasionally, asteroids drift toward the sun and end up colliding with the inner planets. When an asteroid enters Earth's atmosphere, it becomes a meteoroid. If it remains intact after the collision, it becomes a meteorite. Of the tens of thousands of meteorites collected on earth, more than 99 percent originated in the asteroid belt. According to NASA, scientists believe that asteroids delivered water and organic compounds to a newly-formed Earth.