Yin yoga is style of yoga that is the opporsite to the yang practice of any vinyasa practice, or heat generating practice. While the yang practice of vinyasa focuses more on the engagement of muscles to hold the joints together when they are heated, the yin does not. The primary focus of yin is the connective tissue in the joints and the myofascial sheath encompassing the whole of the body. There is many ways that yin can be taught, with one of them being to focus on the energy meridians moving through the physical body and connecting organs such as the kidney, liver, gallbladder, lungs, and so on.
The postures in yin yoga are held for a much longer period of time with an attitude of surrendering to the unseen force of gravity as we experience it. Within a posture you have many objects to turn your awareness towards such as the breath, sensations or the emotions being activated by working on a particular meridian. The yin yoga practice has its roots in history, probably dating back way before modern day religion of the patriarch (yang) into the time of the feminine (yin) when we honoured our mother earth.