Amida Buddha is one of the Five Wisdom Buddhas. "Amida" is the Japanese form of the Sanskrit "Amita," meaning "Immeasurable One." Amida is also known as Amitabha (Sanskrit for "Immeasurable Light") and Amitayus (Sanskrit for "Immeasurable Life").
Amida Buddha is the central figure of Pure Land Buddhism, a Mahayana sect that is extremely popular throughout Japan, China and Korea. It is believed that before his enlightenment, Amida made rebirth in the Western Paradise (or Pure Land) available to anyone who calls on his name in faith.
According to tradition Amitabha was in ancient times a king who, having come in contact with the Buddhist teaching, renounced his throne and became a monk with the name of Dharmakāra. He resolved to become a Buddha and in this way to come into possession of a paradise in which all who call his name might be born into a life of unbounded joy. This is the result of his 48 vows, the most important of which are the 18th and 19th, in which he promises not to achieve supreme perfect enlightenment until he has saved all sentient beings in his paradise. The basic doctrine concerning Amitabha and his vows can be found in the Amitābha-sūtra and the Infinite Life Sutra.
In iconography, Amitabha can be very difficult to tell apart from Shakyamuni, as both possess all the attributes of a Buddha but have no distinguishing marks. He can, however, often be distinguished by his mudra: Amitabha is often depicted with the meditation mudra (as in the Kamakura statue) or the exposition mudra, while the earth-touching mudra is reserved for Shakyamuni alone.
Amitabha is usually portrayed as having two assistants: Avalokiteśvara (Guan Yin) who appears on his right and Mahāsthāmaprāpta who appears on his left, although the order is reversed in Esoteric Buddhism. He is also one of the five buddhas of the vajradhātu.
The Tibetan mantra of Amitabha is 'Om ami dhewa hri'. Various mantras invoking his name are commonly used by modern Amidist schools, particularly Nàmó Āmítuó fó (Chinese) and Namu Amida butsu (Japanese).