The Buddha (also known as Siddhartha Gotama or Siddhārtha Gautama)^{[note 3]} was a philosopher, mendicant, meditator, spiritual teacher, and religious leader who lived in Ancient India (c. 5th to 4th century BCE).^{[note 4]} He is revered as the founder of the world religion of Buddhism, and worshiped by most Buddhist schools as the Enlightened One who has transcended Karma and escaped the cycle of birth and rebirth. He taught for around 45 years and built a large following, both monastic and lay. His teaching is based on his insight into duḥkha (typically translated as "suffering") and the end of dukkha – the state called Nibbāna or Nirvana.

The Buddha was born into an aristocratic family, in the Shakya clan but eventually renounced lay life. According to Buddhist tradition, after several years of mendicancy, meditation, and asceticism, he awakened to understand the mechanism which keeps people trapped in the cycle of rebirth. The Buddha then traveled throughout the Ganges plain teaching and building a religious community. The Buddha taught a middle way between sensual indulgence and the severe asceticism found in the Indian śramaṇa movement. He taught a spiritual path that included ethical training and meditative practices such as jhana and mindfulness. The Buddha also critiqued the practices of Brahmin priests, such as animal sacrifice.

A couple of centuries after his death he came to be known by the title Buddha, which means "Awakened One" or "Enlightened One". Gautama's teachings were compiled by the Buddhist community in the Suttas, which contain his discourses, and the Vinaya, his codes for monastic practice. These were passed down in Middle-Indo Aryan dialects through an oral tradition. Later generations composed additional texts, such as systematic treatises known as Abhidharma, biographies of the Buddha, collections of stories about the Buddha's past lives known as Jataka tales, and additional discourses, i.e, the Mahayana sutras.