A planet is a fairly large object that has a star as the focus of its orbit. The sun has nine planets, the four inner terrestrial planets (Mercury, Venus, Earth, and Mars), four gas giants (Jupiter, Saturn, Uranus, and Neptune) and Pluto, which may be just a large inner member of the Kuiper Belt of asteroids.
The terrestrial planets are small rocky bodies relatively close to the sun. They tend to have few or no moons. The gas giants are big cold balls of gas with small rocky cores. They tend to have many moons.
[TB] {SL}