Asteroids are small bodies that orbit the sun. These are mostly composed of rocky material.
The "asteroid belt" is an especially rich region of our solar system between the orbits of Mars and Jupiter where many asteroids orbit the sun.
We see a large number of asteroids located near the orbit of Jupiter, but leading or trailing Jupiter's position by about 60°. These are held in their relative position due to the gravitational interaction with Jupiter. They are said to be near Jupiter's LaGrange points where the total gravitation between the Sun and Jupiter leads to relatively stable positions. The asteroids leading Jupiter's orbit are referred to as the 'Greek' asteroids and those trailing Jupiter's orbit are called the 'Trojan' asteroids. One other group of asteroids near Jupiters L3 LaGrange point are called the Hilda asteroids, or collectively, the Hildae.