Medieval “Hinduism,” like modern Indian orthodoxy, was largely Tantric. Tantra, being the main source of fundamental concepts such as worship, images, initiation, yoga, and the supremacy of the Guru, continues to play a significant role. However, not all injunctions in the Sastra are universally accepted. This introduction is a brief overview, with a more detailed exploration planned for a future volume focusing on rituals. An accurate statement of facts is needed, as current accounts of Tantra are often superficial and condemnatory.