Hatha yoga can refer to either the physical practice of asana (yoga postures) and pranayama (breathing techniques), or to the eightfold path of mind-body disciplines described in Patanjali’s Yoga Sutras. Hatha yoga as a type of exercise was brought to the Western world in the twentieth century and is the tradition from which the Ashtanga, Iyengar, and Vinyasa styles came. In Hatha yoga, the postures are held for longer periods, and sessions may include breathing and meditation practices.