Maithuna is the term for ritual sexual union as it appears in certain tantric traditions of Hinduism and Buddhism, the last and most secret of the five transgressive elements of the "left-hand" tantric rite. In this restricted context, the sexual act is not pursued for pleasure or procreation but is undertaken as a controlled ritual by initiated practitioners, framed by elaborate preparation, visualisation and the deliberate identification of the partners with a deity and consort, so that the union enacts on the human plane the cosmic union of the divine masculine and feminine principles from whose interplay, in tantric thought, all reality arises. The practice aims, in its own understanding, at the transformation of the powerful energies of desire into a means of liberation rather than bondage, harnessing what ordinary religion shuns.
Several cautions are essential to describing maithuna accurately. Within the tantric traditions themselves it is a rare, highly restricted and closely guarded practice, hedged with initiation, secrecy and strict discipline, confined to qualified adepts and often understood symbolically or internally, as the union of energies within the practitioner's own body, rather than performed literally. It is emphatically not representative of tantra as a whole, the vast bulk of which consists of mantra, ritual, visualisation and yogic discipline with no sexual element. And it is quite distinct from the modern Western "tantric sex" or "sacred sexuality" movements, which borrow the vocabulary of maithuna but are largely twentieth-century constructions only loosely connected to the historical traditions and their demanding ascetic and initiatory frame. Scholars stress that the ritualised, disciplined and often symbolic maithuna of the tantric texts must not be conflated with the popular Western reinterpretation that trades on its name.