Yin yoga, so named because of its correspondence to the Taoist concept of yin, is a very distinct style of Chinese yoga similar to hatha yoga that stretches the connective tissue (joints) rather than conditioning the muscles, the latter being the aim of most other styles of hatha yoga. Experientially, the practice is characterized by passive asanas held for several minutes each. Some believe that yin yoga is the oldest form of hatha yoga, since it is the ideal method of physical conditioning for prolonged meditation, which is the principle concern of the ancient Hindu practice of raja yoga.
Yin yoga has been popularized in Western Culture by teachers Paul Grilley and Sarah Powers. The teachings of Paul Grilley incorporate ideas related to traditional Chinese medicine and qigong, such as Taoist yoga and meridians. The practice is called yin, as opposed to yang, because it corresponds with yin attributes such as substance (as opposed to activity), passive posturing (as opposed to active movement), cold (as opposed to hot) and other such qualities. It has been differentiated from "yang" yoga just as many physical practices in China are divided into yin and yang schools, the yin schools being softer and less aggressive. Yin yoga, as it is commonly taught in the West, is now associated with these Chinese practices. Yin yoga is often used to improve the flow of qi through the body.
Yin yoga is often prescribed as a method of preparing for meditation postures, specifically lotus position(called the butterfly, in Taoist yoga), which require flexibility in the connective tissue.
The Yin yoga community continues to grow, it has become very popular in the big cities in China like Shanghai, Beijing, etc..
Recently, I completed Laura Kupperman's Yin Yoga Self Study Program and am now able to teach Yin Yoga at CorePower Yoga. Being a body worker, it is clear to me that every person can benefit from this type of yoga style. Being a perfect compliment to other kinds of Yang Yoga, I highly recommend trying it out. One and one and group sessions available...