Acharya, from the Sanskrit for one who teaches by personal example, denotes a spiritual and philosophical teacher within Hinduism whose authority rests on demonstrated mastery of scripture and philosophy together with the personal conduct considered inseparable from genuine teaching in Hindu tradition, reflecting the term's own etymology: an acharya teaches acara, right conduct, through example rather than instruction alone. The title is used both as a standalone designation for a respected teacher heading an ashram, school or specific philosophical lineage, and as an honorific suffix appended to the names of Hinduism's most historically influential philosophers and founders of specific schools of Vedanta, most famously Adi Shankaracharya, Ramanujacharya and Madhvacharya, whose differing interpretations of the Upanishads and the Brahma Sutras established the three most historically influential schools of Vedantic philosophy, Advaita, Vishishtadvaita and Dvaita respectively.
Modern usage of acharya has broadened considerably to include heads of educational institutions, teachers of specific arts or sciences within a traditional guru-shishya framework, such as an acharya of classical music or of Ayurveda, and, in some contemporary contexts, a formal academic or institutional title conferred by a specific Hindu organization on a qualified teacher, reflecting the term's underlying flexibility as a marker of recognized teaching authority applicable well beyond the small number of historically foundational philosophical acharyas.