"Yoga is fourfold: faith, aspiration, perseverance and means"
Yogācārabhūmi-Śāstra
(Sravakabhumi), a Mahayana
Buddhist Yogacara work
What is often referred to as Classical Yoga, Astanga (Yoga of eight limbs), or Raja Yoga is mainly the type of Yoga outlined in the highly influential Yoga Sutras of Patanjali. The origins of the Classical Yoga tradition are unclear, though early discussions of the term appear in the Upanishads.
Buddhist yoga encompasses an extensive variety of methods that aim to develop key virtues or qualities known as the 37 aids to awakening.
Jain yoga has been a central practice in Jainism. Jain spirituality is based on a strict code of nonviolence or ahimsa (which includes vegetarianism), almsgiving (dana), right faith in the three jewels, the practice of austerities (tapas) such as fasting, and yogic practices.
Learn more about Yoga on Wikipedia.