Rebirth refers to a process whereby beings go through a succession of lifetimes as one of many possible forms of sentient life, each running from conception to death. In Buddhist thought, this rebirth does not involve any soul, because of its doctrine of anattā (Sanskrit: anātman, no-self doctrine) which rejects the concepts of a permanent self or an unchanging, eternal soul, as it is called in Hinduism and Christianity. According to Buddhism there ultimately is no such thing as a self in any being or any essence in any thing.
The Buddhist traditions have traditionally disagreed on what it is in a person that is reborn, as well as how quickly the rebirth occurs after each death. Some Buddhist traditions assert that “no self” doctrine means that there is no perduring self, but there is avacya (inexpressible) self which migrates from one life to another. The majority of Buddhist traditions, in contrast, assert that vijñāna (a person’s consciousness) though evolving, exists as a continuum and is the mechanistic basis of what undergoes rebirth, rebecoming and redeath. The rebirth depends on the merit or demerit gained by one’s karma, as well as those accrued on one’s behalf by a family member.
Each rebirth takes place within one of five realms according to Theravadins, or six according to other schools – heavenly, demi-gods, humans, animals, hungry ghosts and hellish.
In East Asian and Tibetan Buddhism, rebirth is not instantaneous, and there is an intermediate state (Tibetan “bardo”) between one life and the next. The orthodox Theravada position rejects the wait, and asserts that rebirth of a being is immediate. However there are passages in the Samyutta Nikaya of the Pali Canon that seem to lend support to the idea that the Buddha taught of an intermediate stage between one life and the next.