A giant planet is any massive planet. They are usually primarily composed of low-boiling-point materials (gases or ices), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars.
There are only four giant planets
the statement only states that there are four known giant planets, and went further to state that there are many extrasolar giant planets have been identified orbiting other stars.
