The inner planets of the Solar System are Mercury, Venus, Earth and Mars. The Sun also counts as one. They are the inner planets because they have dense, rocky compositions, few or no moons, and no ring systems.
The outer planets of the Solar System are Jupiter, Saturn, Uranus, and Neptune. All of these planets have ring systems and have moons . E.g. Jupiter has 64 known moons .
Pluto is an ex. Planet. Due to it’s size astronomers called it a dwarf planet.