Meteoroids are small bodies that travel through space. Meteoroids are smaller than asteroids; most are smaller than the size of a pebble.
A meteor is a meteoroid that has entered the Earth's atmosphere, usually making a fiery trail as it falls. A meteor shower (pictured at the left) is a phenomenon in which many meteors fall through the atmosphere in a short time.
A meteorite is a meteor that has fallen to Earth. These objects have survived a fiery fall through the Earth's atmosphere and have lost a lot of mass during that process.