Buddhism is a philosophy and/or religion based on the teachings of the Buddha, Siddhārtha Gautama (Sanskrit; in Pāli, Siddhattha Gotama), who lived between approximately 563 and 483 BCE. Originating in India, Buddhism gradually spread throughout Asia to Central Asia, Tibet, Sri Lanka, Southeast Asia, as well as the East Asian countries of China, Mongolia, Korea, and Japan.

The aim of buddhist practices is to become free of suffering (dukkha). Some schools emphasize awakening the practitioner to the realization of anatta (egolessness, the absence of a permanent or substantial self) and achieve enlightenment and Nirvana. Other Buddhist scriptures (the "Tathagatagarbha" sutras) encourage the practitioner to cleanse him/herself of the mental and moral defilements of the "worldly self" and thereby penetrate through to a perception of the indwelling "Buddha-Principle" ("Buddha-nature"), also termed the "True Self" (see "Mahayana Mahaparinirvana Sutra"), and thus become transformed into a Buddha. Some other schools appeal to bodhisattvas for a favourable rebirth. Some others do none of these things. Most, if not all, Buddhist schools also teach followers to perform good and wholesome actions, to avoid bad and harmful actions. There can be very large differences between different Buddhist schools of thought.

Buddhist morality is underpinned by the principles of harmlessness and moderation. Mental training focuses on moral discipline (sila), meditative concentration (samadhi), and wisdom (prañā).

Buddhism, per se, neither confirms nor denies the existence of the supernatural (gods, demons, heavens, hells, etc.). Some Buddhist schools do employ deities and celestial protectors in their practices, but these are generally considered to be emanations of the meditator's own mind and thus not fundamentally real.