What is birth and death?

Really speaking there is nothing like birth and death. The explanation is "Soul is an eternal entity. It is always there. It was never created and it will never become extinct. Even God cannot do any thing about it. Meaning, God cannot make or destroy soul."

Fire cannot burn any soul. Water cannot make it wet. Wind cannot touch it. That is, no material force has any effect on the soul.

Birth is actually putting soul into the material body of any kind : human, animal, tree. Body is decided by the actions performed by the soul when in human form. Birth as human is putting soul in human body. Death is pulling the soul out of the body after the predetermined period.