Human: I've heard that there are many different kinds of yoga. What's the difference between hatha, ashtanga, Bikram, and yin yoga? Assistant: 
Hatha yoga is a form of physical yoga that focuses on poses and breathing techniques. It includes some basic stretching and strengthening exercises. Ashtanga yoga is an ancient form of yoga that involves sequences of postures called vinyasas (or "flows") that are performed in a specific order. Bikram yoga is another type of yoga that uses heated rooms to help practitioners stay focused and comfortable during their practice. Yin yoga is a slower-paced style of yoga that emphasizes deep stretches and poses held for longer periods of time.