Tantra in Sanskrit means “woven together”. It is a term loosely applied to several divergent and even contradictory schools of Hindu yoga in which the sexual union of male and female is worshiped.
It has also come to be applied to sex-based religious practices developed in other religions, including Bon, Tibetan Buddhism, Taoism, Christianity, Judaism, and Transcendentalism.
The earliest strand of tantra yoga is derived from the pre-Hindu religion of Shaktiism. This centers around worship of the goddess in her numerous forms, and focuses on a ceremony honoring the vulva — either of a statue or a living woman.
Depending upon the school of study, this puja may involve making offerings of food and liquids while chanting prayers or it may involve the deliberate sexual arousal of a woman who is believed to embody or personify the deity.
A related thread of tantra yoga that derives from Shaivism has at its center linga puja, a ceremony honoring the penis, often in the form of a natural upright stone.
Similar objects of worship have been found among the archaeological remains of many neolithic people around the world, leading some theorists to speculate that “sex worship” in some form or another is humanity’s oldest religion.