In Sanskrit texts, Rāja yoga (ˈrɑːdʒə_ˈjoʊgə; राजयोग) was both the goal of yoga and a method to attain it. The term also became a modern name for the practice of yoga in the 19th-century when Swami Vivekananda gave his interpretation of the Yoga Sutras of Patanjali in his book Raja Yoga. Since then, Rāja yoga has variously been called aṣṭāṅga yoga, royal yoga, royal union, sahaja marg, and classical yoga.
Rāja (Sanskrit: राज) means "chief, best of its kind" or "king". Rāja yoga thus refers to "chief, best of yoga".
The historical use of the term Rāja yoga is found in other contexts, quite different from its modern usage. In ancient and medieval Sanskrit texts, it meant the highest state of yoga practice (one reaching samadhi). The Hatha Yoga Pradipika, for example, states that Hatha yoga is one of the ways to achieve Rāja yoga.
Rāja yoga is discussed in the Yogatattva Upanishad. It is then mentioned in a 16th-century commentary on a specific step in the Yoga Sūtras of Patañjali. The medieval era Tantric work Dattātreyayogaśāstra explains in 334 shlokas the principles of four yogas: Mantra yoga, Hatha yoga, Laya yoga and Raja yoga. Alain Daniélou states that Rāja yoga was, in the historic literature of Hinduism, one of five known methods of yoga, with the other four being Hatha yoga, Mantra yoga, Laya yoga and Shiva yoga. Daniélou translates it as "Royal way to reintegration of Self with Universal Self (Brahman)".
The term became a modern retronym in the 19th-century when Swami Vivekananda equated raja yoga with the Yoga Sūtras of Patañjali. This meaning is different from that in the Hatha Yoga Pradīpikā, a text of the Natha sampradaya.
The method of meditation followed under Sahaj Marg, also called Heartfulness follows Raja Yoga system of practice. This system is in practice formally since 1945 under the name Shri Ram Chandra Mission (SRCM).
The Brahma Kumaris, a new religious movement, teaches a form of meditation it calls "Raja yoga" that has nothing to do with either the precepts of Hatha Yoga or Patañjali's Yoga Sūtras.