Have you ever thought about how our planet Earth came into existence? What was the first life form that existed on Earth billions of years before the humans came into existence? What caused the extinction of dinosaurs? For how recent have the humans appeared on Earth as compared to the age of planet Earth? These are some of the mind boggling questions that raise curiosity. Let's find out the complete history of earth, from the time Earth came into existence billions of years ago to the present time.