Ashtanga yoga is a style of yoga that emphasizes the linking of movement and breath, Ujjayi breathing, and bandhas (energy locks) . It is a physically demanding form of yoga that is often promoted as a dynamic form of classical Indian (hatha) yoga. Ashtanga yoga is made up of six series or levels, with a fixed order of postures. Students follow a set sequence of postures each time, gradually progressing through the series. The individual poses (asanas) are linked by flowing movements (vinyasas) . Ashtanga yoga is based on the eight-limbed path of yoga philosophy of Patanjali, which represents the various branches of the philosophy of the yoga sutras. The current style of teaching is called "Mysore style," after the city in India where the practice was originally taught. Ashtanga yoga is a very dynamic and athletic form of yoga that demands an intense level of physical strength, flexibility, and endurance.