Reincarnation, also known as rebirth, transmigration, or metempsychosis (Greek) is the philosophical or religious concept that the non-physical essence of a living being begins a new life in a different physical form or body after biological death. Resurrection is a similar process hypothesized by some religions in which a soul comes back to life in the same body. In most beliefs involving reincarnation, the soul is seen as immortal and the only thing that becomes perishable is the body. Upon death, the soul becomes transmigrated into a new infant or animal to live again. The term transmigration means passing of soul from one body to another after death.

Reincarnation (Punarjanma) is a central tenet of the Indian religions such as Hinduism, Buddhism, Jainism, and Sikhism; as well as certain Paganist religious groups, although there are Hindu and Buddhist groups who do not believe in reincarnation, instead believing in an afterlife. In various forms, it occurs as an esoteric belief in many streams of Judaism in different aspects, in some beliefs of the Indigenous peoples of the Americas, and some Indigenous Australians (though most believe in an afterlife or spirit world). A belief in rebirth/metempsychosis was held by Greek historical figures, such as Pythagoras, Socrates, and Plato, as well as in various modern religions.

Although the majority of denominations within Christianity and Islam do not believe that individuals reincarnate, particular groups within these religions do refer to reincarnation; these groups include the mainstream historical and contemporary followers of Cathars, Alawites, the Druze, and the Rosicrucians. The historical relations between these sects and the beliefs about reincarnation that were characteristic of Neoplatonism, Orphism, Hermeticism, Manichaenism, and Gnosticism of the Roman era as well as the Indian religions have been the subject of recent scholarly research. In recent decades, many Europeans and North Americans have developed an interest in reincarnation, and many contemporary works mention it.