Tantra is that Asian body of beliefs and practices which, working from the principle that the universe we experience is nothing other than the concrete manifestation of the divine energy of the godhead that creates and maintains that universe, seeks to ritually appropriate and channel that energy, within the human microcosm, in creative and emancipatory ways.
(David Gordon White - Tantra in Practice)
Tantras are divided into
Hindu Tantra
Buddhist Tantra
Jain Tantra
even though there is an overlap between these schools.
Information about the Yoga part of Tantra.
System concerning body, mind, consciousness and soul founded by Paramhans Swami Maheshwarananda. Offers news, online community resources, links and philosophy. http://www.yoga-in-daily-life.org/