In Buddhism, Buddha (/ˈbuːdə, ˈbʊdə/, which in classic Indic languages means "awakened one") is a title for those who are spiritually awake or enlightened, and have thus attained the supreme goal of Buddhism, variously described as awakening or enlightenment (bodhi), Nirvāṇa ("blowing out"), and liberation (vimokṣa). A Buddha is also someone who fully understands the Dhārma, the true nature of all things or phenomena (dhārmata), the ultimate truth. Buddhahood (Sanskrit: buddhatva; Pali: buddhatta or buddhabhāva; Chinese: 成佛) is the condition and state of being a Buddha. This highest spiritual state of being is also termed sammā-sambodhi (Sanskrit: samyaksaṃbodhi; "full, complete awakening" or “complete, perfect enlightenment”) and is interpreted in many different ways across schools of Buddhism.

The title of "Buddha" is most commonly used for Gautama Buddha, the historical founder of Buddhism, who is often simply known as "the Buddha". The title is also used for other sentient beings who have achieved awakening or enlightenment (bodhi) and liberation (vimokṣa), such as the other human Buddhas who achieved enlightenment before Gautama; members of the Five Buddha Families such as Amitābha; and the bodhisattva Maitreya, known as the "Buddha of the future who will attain awakening at a future time."

In Theravāda Buddhism, a Buddha is commonly understood as a being with the deepest spiritual wisdom about the true nature of reality, who has transcended rebirth and all causes of suffering (duḥkha). He is also seen as having many miraculous and magical powers. However, a living Buddha has the limitations of a physical body, will feel pain, get old, and eventually die like other sentient beings. In Mahāyāna Buddhism, any Buddha is considered to be a transcendent being with extensive powers, who is all-knowing, immeasurably powerful, with an eternal lifespan. His wisdom light is said to pervade the cosmos, and his great compassion and skillful means are limitless. This transcendent being is not understood as having a normal physical human body; instead, Mahāyāna Buddhism defends a kind of docetism, in which Gautama Buddha's life on earth was a magical display which only appeared to have a human body.

A sentient being who is on the path to become a Buddha is called a bodhisattva. In Mahāyāna Buddhism, Buddhahood is the universal goal and all Mahāyānists ultimately aim at becoming a Buddha, in order to benefit and liberate all sentient beings. Thus, Buddhahood is the goal for all the various spiritual paths found in the various Mahāyāna traditions (including Tantric Buddhism, Zen, and Pure Land). This contrasts with the common Theravādin goal of individual liberation, or arhatship.

Buddhahood is the state of an awakened being, who, having found the path of cessation of suffering (duḥkha) (as originated from attachment to fetters and hindrances, distorted perception and thinking) is in the state of "no-more-Learning".

Buddhism is devoted primarily to awakening or enlightenment (bodhi), Nirvāṇa ("blowing out"), and liberation (vimokṣa) from all causes of suffering (duḥkha) due to the existence of sentient beings in saṃsāra (the cycle of compulsory birth, death, and rebirth) through the threefold trainings (ethical conduct, meditative absorption, and wisdom). Classical Indian Buddhism emphasized the importance of the individual's self-cultivation (through numerous spiritual practices like keeping ethical precepts, Buddhist meditation, and worship) in the process of liberation from the defilements which keep us bound to the cycle of rebirth. According to the standard Buddhist scholastic understanding, liberation arises when the proper elements (dhārmata) are cultivated and when the mind has been purified of its attachment to fetters and hindrances that produce unwholesome mental factors (various called defilements, poisons, or fluxes).

There is a broad spectrum of opinion on the nature of Buddhahood, its universality, and the method of attaining Buddhahood among the various schools of Buddhism. The level to which this manifestation requires ascetic practices varies from none at all to an absolute requirement, dependent on doctrine. In Mahāyāna Buddhism, Buddhahood is the universal goal and all Mahāyānists ultimately aim at becoming a Buddha, in order to benefit and liberate all sentient beings. While most Mahāyāna Buddhist schools accept the bodhisattva ideal, in which it takes aeons to reach Buddhahood, not all agree that everyone can become a Buddha or that the path to Buddhahood must necessarily take aeons.

In Theravāda Buddhism, Buddha refers to one who has reached awakening or enlightenment (bodhi) through their own efforts and insight, without a teacher to point out the Dhārma. A samyaksaṃbuddha ("full, complete Buddha") re-discovers the Four Noble Truths and the Noble Eightfold Path to awakening on their own, and then teaches these to others after his awakening. A pratyekabuddha ("solitary Buddha") also reaches Nirvāṇa through his own efforts, but is unable or unwilling to teach the Dhārma to others. An arhat ("saint") needs to follow the teaching of a Buddha to attain Nirvāṇa, and may also preach the Dhārma after attaining Nirvāṇa. In one instance the term Buddha is also used in Theravādin literature to refer to all who attain Nirvāṇa, using the term śrāvakabuddha to designate an arhat, someone who depends on the teachings of a Buddha to attain Nirvāṇa. In this broader sense it is equivalent to the arhat.