What was earth created by?
About 4.5 billion years ago, after our sun (star) came into being, it captured within its gravitational field all the gases and materials needed to form all the planets, the asteroids of both the inner asteroid zone and the Kuiper belt beyond the orbit of Pluto.
In those early years while formation was going on, dust collided with dust, rocks with rocks, and even planets with planets. These collisions cause the release of large amounts of energy which for the four rocky inner planets meant they were little more than balls of molten rock. The earth was this way. From 4.5 to 3.5 billion years ago the earth, and other planets that had formed, where constantly bombarded by asteroids and comets.
It is speculated that the existence of water on the Earth, Mars, Venus and possibly the moon, all came from comets that collided with this planets those billions of years ago. As the collisions subsided, the earth cooled and began to form what we know today.