Rebirth in Buddhism refers to its teaching that the actions of a person lead to a new existence after death, in endless cycles called saṃsāra. This cycle is considered to be dhukkha, unsatisfactory and painful. The cycle stops only if liberation is achieved by insight and the extinquishing of desire. Rebirth is one of the foundational doctrines of Buddhism, along with Karma, nirvana and moksha.
The rebirth doctrine in Buddhism, sometimes referred to as reincarnation or metempsychosis, asserts that rebirth does not necessarily take place as another human being, but as an existence in one of the six Gati (realms) called Bhavachakra. The six realms of rebirth include Deva (heavenly), Asura (demigod), Manusya (human), Tiryak (animals), Preta (ghosts), and Naraka (resident of hell). This rebirth, state Buddhism traditions, is determined by karma, with good realms favored by Kushala (good karma), while a rebirth in evil realms is a consequence of Akushala (bad karma). While Nirvana is the ultimate goal of Buddhist teaching, much of traditional Buddhist practice has been centered on gaining merit and merit transfer, whereby one gains rebirth in the good realms and avoids rebirth in the evil realms.
The rebirth doctrine has been a subject of scholarly studies within Buddhism since ancient times, particularly in reconciling the rebirth doctrine with its Anatman (no self, no soul) doctrine. The Buddhist traditions have 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 Vijnana (a person's consciousness) though evolving, exists as a continuum and is the mechanistic basis of what undergoes rebirth, rebecoming and redeath. Some traditions assert that the rebirth occurs immediately, while others such as the Tibetan Buddhism posits an interim state wherein as many of 49 days pass between death and rebirth and this belief drives the local funerary rituals.
There is no word corresponding exactly to the English terms "rebirth", "metempsychosis", "transmigration" or "reincarnation" in the traditional Buddhist languages of Pāli and Sanskrit. Rebirth is referred to by various terms, representing an essential step in the endless cycle of samsara, terms such as "re-becoming" or "becoming again"(Sanskrit: punarbhava, Pali: punabbhava), re-born (punarjanman), re-death (punarmrityu), or sometimes just "becoming" (Pali/Sanskrit: bhava), while the state one is born into, the individual process of being born or coming into the world in any way, is referred to simply as "birth" (Pali/Sanskrit: jāti). The entire universal process of beings being reborn again and again is called "wandering about" (Pali/Sanskrit: saṃsāra).