Classical Hatha Yoga works postures (asanas) with the breath, to bring about the desired effect, whereby working the body physically you bring about a relaxation of body and mind. Students come to yoga for many reasons: to improve general fitness, flexibility and for its stress relief and relaxation benefits.
Surya Namaskar, the Sun Salutation, is a series of twelve asanas worked with the breath. This is a wonderful way to warm up the body, getting the blood flowing to the muscles and is very energising, we do this at the beginning of a practice.