Vinyasa is a breathing and movement system maintained during asana practice to generate internal cleansing. Each movement in a series of asanas is synchronised with the breath, which helps guide the body into lightness and alignment, focusing the mind and internalizing the awareness. One breath equals one movement. All asanas are assigned a certain number of vinyasas. For example, in Surya Namaskara A there are nine vinyasas. The first vinyasa is inhaling and raising the arms above the head with the palms pressed together. The second vinyasa is exhaling and folding forward and placing the hands besides the feet, and so on and so forth. For the beginner the correct number of vinyasas may not be possible. This is appropriate as long as the practitioner adheres to the correct inhalation and exhalation movements. With time and practice the correct vinyasas will become possible.
In asana practice, vinyasa is the foundation of our inner purification. By moving and breathing together the blood is heated, which removes disease causing impurities from the blood and makes the blood thinner and lighter, so that it may circulate freely. As Sri Patthabi Jois said, vinyasa will "boil the blood". Vinyasa causes us to sweat, which is the vehicle by which the toxins are removed from our bodies, leaving the body pure, strong, light, and healthy. After the body becomes pure, we can then work to purify the nervous system and the mind. In this sense Vinyasa is the foundation for our complete purification.