Regulating the breath is an important part of yoga practice. Descriptions in traditional yoga texts mention breath regulation as a way of getting spiritual realization. In yoga, there are several ways to modify breathing, such as changing the rate and depth, holding the breath, breathing through the mouth, or breathing alternately through one or both nostrils. These voluntarily regulated yoga breathing techniques are called pranayamas in Sanskrit. Brief descriptions of these techniques in traditional yoga texts as well as their physiological effects are given here.