Big Bang Theory

Everyone on this earth have that question in mind which constantly keeps hitting them like, tell me, tell me now, how was the universe created, how did it actually came into existence, how are they present here, how long are they going to stay here or what is going to happen in future with this earth. But never really got any answer to this, although according to scientific studies, there is one theory which explains some points that somehow makes answer valid for our brains. And this theory is what you can call as, big bang theory.