Vinyasa and yin are two very different but complimentary styles of yoga. Although there are some overlaps and some of the postures can even look exactly the same, the intention behind each of these practices is very different.
You may be much more familiar with vinyasa as it is one of the more popular styles in the western world. It is characterized by stringing postures together in a flowing sequence that connects breath to movement.
The vinyasa we know today stems from the traditional Ashtanga Vinyasa which is a set series of postures where students practice at their own pace under the guidance of their teacher. Known to be a vigorous practice, ashtanga vinyasa builds heat in the body and resilience in the mind.
In modern vinyasa, no two sequences are alike, leaving plenty of room for creativity and exploration of different themes, intentions, and intensity. Depending on the teacher and class you might experience a more gentle slow flowing practice or a high intensity power yoga practice, and yet both are still called vinyasa.
In both ashtanga vinyasa and modern vinyasa it is a common practice to warm up the body with sun salutations and to keep the body warm throughout the practice by "taking a vinyasa." Sun salutations are a sequence of specific postures that warm up the front and back chains of the body and the major muscle groups. A "vinyasa" is a sequence that includes plank, chaturanga, cobra or upward facing dog, and downward facing dog, and is often taken between sides in a flow sequence or to "clear the palette" for what is coming next. It is also part of the Sun Salutations warm-up sequence.
Unlike ashtanga vinyasa where you always take a prescribed amount of sun salutations and vinyasas, in a modern vinyasa class that number can vary depending on the purpose of the class. Teachers may also add in variations to these sequences.
Movement and the transition between postures is just as important in a vinyasa practice as the posture itself and therefore it is common that vinyasa classes are fast paced, with less time spent holding each pose than in some other styles of yoga. It is precisely this that makes vinyasa "yang" in nature, as are most movement practices. We can think of vinyasa yoga as a kind of moving meditation.
Yin yoga, on the other hand, is a practice of stillness, surrender and acceptance. It is characterized by long, passive holds, of postures that are mostly done seated or lying down. The poses are held mostly in silence, creating the conditions for a quiet, introspective practice.
Unlike vinyasa yoga, which targets the muscles, the long, passive holds in yin yoga put a healthy compression on the joints, connective tissues and fascia. Yin yoga is often called the "yoga of the joints," as it can increase mobility, and is therefore highly beneficial, especially for the aging population, where mobility naturally decreases, making the body more prone to injury. As we age, our once "juicy" fascia also loses a lot of its' moistness, which can create stiffness in the body. Yin yoga revives the fascia and can therefore help restore our body's flexibility.
Because we don't want the muscles to "steal the show," yin yoga is often practiced without warming up, ideally in the morning before we have done too much moving around. That doesn't mean you can't practice at night or after a yang practice. It just means that the benefit you receive, will be more the calming introspection, rather than the compression of the joints.
Our intention in yin is to hold the posture with as little muscular effort as possible, letting the shape, gravity and time do the work for you.
A common misconception about yin yoga, however, is that it is easy. While some of it can certainly feel that way, yin yoga can be the opposite, especially since being in constant motion is a common tendency in our culture. For many people, taking that moment to pause and be still can stir up a lot of emotions. This is why there are three main principles to yin yoga.
The first principle of yin yoga is to find your edge. This means to find the level of intensity where you feel some sensation but not pain. On a scale of 1 to 10 (1 being no sensation and 10 being pain), we want to find this edge around a 4 or a 5, unlike vinyasa yoga where we might push ourselves to find that edge around a 7.