Yin Yoga is a practice which embodies the opposite of a usual active (Yang) practice. Yang means activation, dynamic movement, fire, masculine energy, and power. Yin means quietness, stillness, introspection, feminine energy and softness.
Yin yoga is the slow and soft style of yoga. The Yoga poses (Āsana) are held for longer periods of time than a usual Yoga practice, so, a Yin Yoga practice is one that pays attention to holding poses in stillness for extended periods of time and of focusing inward, observing the fluctuations of the mind. This itself can help practitioners to achieve meditative states and often aids those who struggle to meditate to access its benefits.
The physical effects of Yin Yoga are also different than a regular Yoga practice. Yin Yoga works by releasing tension in the connective tissues of the body, working into those tight areas of Fascia (our web of connective tissues) and the joints. For those people who have very tight stiff areas in the body this practice can really help to open up the body in ways that a regular Yoga practice might not because in these hard to access areas a Yoga practitioner might have stored unreleased emotions, fears and worries. By holding still and releasing the tension for the body as well as the mind a practitioner of Yin Yoga can witness big positives changes in their emotional and mental state as well as their physical one.