Taoism (modernly: Daoism) is a philosophical and religious tradition that emphasizes living in harmony with the Tao (modernly romanized as "Dao"). The term Tao means "way", "path" or "principle", and can also be found in Chinese philosophies and religions other than Taoism. In Taoism, however, Tao denotes something that is both the source and the driving force behind everything that exists. It is ultimately ineffable: "The Tao that can be told is not the eternal Tao."

The keystone work of literature in Taoism is the Tao Te Ching, a concise and ambiguous book containing teachings attributed to Laozi (Chinese: 老子; pinyin: Lǎozi; Wade–Giles: Lao Tzu). Together with the writings of Zhuangzi, these texts build the philosophical foundation of Taoism. This philosophical Taoism, individualistic by nature, is not institutionalized. Institutionalized forms, however, evolved over time in the shape of a number of different schools, often integrating beliefs and practices that even pre-dated the keystone texts – as, for example, the theories of the School of Naturalists, which synthesized the concepts of yin and yang and the Five Elements. Taoist schools traditionally feature reverence for Laozi, immortals or ancestors, along with a variety of divination and exorcism rituals, and practices for achieving ecstasy, longevity or immortality.