Answer:
Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. Volcanic out gassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen.
Step-by-step explanation:
This is what I found but we all have our own opinions so it could be whatever theory you think is best. there is also the biblical way that states that God created the world and everything and then the scientific way is the Big Bang Theory and then we came along during evolution.