Many practicing Yogis have heard of the Patanjali Ashtanga Yoga and the Patanjali Yoga Sutras (http://www.swamij.com/yoga-sutras.htm), which tenets are used mostly in teacher trainings. They incorporate the eight steps to attain ultimate wisdom (http://www.yogajournal.com/artic…/beginners/the-eight-limbs/.
However there is another text less quoted: The Hatha Yoga Pradipika, which is said to be the oldest surviving text on Hatha Yoga. Swami Swatmarama, a disciple of Swami Goraknath, was the author of the text in the 15th century CE.
The text incorporates descriptions of asanas (postures), purifying practices (shatkarma), mudras (finger and hand positions), bandhas (locks), and pranayama (breath exercises). The purpose of Hatha Yoga is explained as the awakening of kundalini (subtle energy) to experience deep meditative absorption known as Samadhi (http://www.yogabasics.com/learn/hatha-yoga-pradipika/).