Overview
Satya (Sanskrit: सत्य; IAST: Satya) is a Sanskrit word usually translated as "truth" or "essence". Across Indian religions, it is regarded as a deeply valued virtue, signifying the alignment of one's thoughts, speech, and actions with reality.
In the traditions of Hinduism, Jainism, Buddhism and Sikhism, satya is held as a guiding principle of ethical conduct. It denotes not only honesty in speech but also a wider commitment to truthfulness in intention and behaviour, so that what one thinks, says and does remains in harmony with what is real.
In Yoga philosophy, particularly in Patañjali's Yoga Sutras, satya is enumerated as one of the five yamas—moral restraints intended to cultivate truthfulness and to prevent the distortion of reality through one's expressions and behaviour. As a yama, it functions as a foundational discipline for practitioners, supporting further stages of yogic practice.
References
Adapted from the English Wikipedia article on Satya.