Find out what Hatha yoga is all about by reading the Hatha Yoga Pradipika.

From Wikipedia

The Hatha Yoga Pradipika (Sanskrit: Ha?hayoga Prad?pik?) is a classic Sanskrit manual on Hatha Yoga, written by Svami Svatmarama, a disciple of Svami Gorakhnath. Said to be the oldest surviving text on the Hatha Yoga, it is one of the three classic texts of Hatha Yoga, the other two being the Gheranda Samhita and the Shiva Samhita.

The text was written in 15th century CE. The work is derived from older Sanskrit texts and Svami Svatamarama’s own yogic experiences. Many modern English translations of the text are available.

The book consists of four Upadeshas (chapters) which include information about asanas, pranayama, chakras, kundalini, bandhas, kriyas, shakti, nadis and mudras among other topics. It runs in the line of Hindu yoga (to distinguish from Buddhist and Jain yoga) and is dedicated to Lord Adinath, a name for Lord Shiva (the Hindu god of destruction and renewal), who is alleged to have imparted the secret of Hatha Yoga to his divine consort Parvati.