Reincarnation is the philosophical or religious concept that the non-physical essence of a living being starts a new life in a different physical form or body after biological death. It is also called rebirth or transmigration, and is a part of the Saṃsāra doctrine of cyclic existence. It is a central tenet of Indian religions, namely Jainism, Buddhism, Sikhism and Hinduism, although there are Hindu groups that do not believe in reincarnation but believe in an afterlife.