Hatha yoga (Sanskrit हठयोग haṭhayoga, IPA: [ɦəʈʰəˈjoːɡə]), also called hatha vidya (हठविद्या), is a system of yoga introduced by Yogi Swatmarama, a sage of 15th century India, and compiler of the Hatha Yoga Pradipika. In this treatise Swatmarama introduces hatha yoga as preparatory stage of physical purification that the body practices for higher meditation. The asanas and pranayama in raja yoga were what the Hindu yogis used to physically train their body for long periods of meditation. This practice is called shatkarma.
The word hatha is a compound of the words ha and tha meaning sun and moon, referring to prana and apana, and also to the principal nadis (energy channels) of the subtle body that must be fully operational to attain a state of dhyana or samādhi. According to the Monier-Williams Sanskrit Dictionary, the word "hatha" means forceful. It is a strong practice done for purification. In other respects hatha yoga follows the same principles as the raja yoga of Patanjali. Hatha yoga is what most people in the Western world associate with the word "yoga" and is most commonly practiced for mental and physical health.
Traditional hatha yoga is a holistic yogic path, including disciplines, physical postures (asana), purification procedures (shatkriya), poses (mudra), breathing (pranayama), and meditation. The hatha yoga predominantly practiced in the West consists of mostly asanas understood as physical exercises. It is also recognized as a stress-reducing practice.
Hatha yoga is one of the two branches of yoga that focuses on the physical culture, the other one being raja yoga. Both of these are commonly referred to as sadanga yoga, i.e., yoga of six parts ('sad' meaning six and 'anga' meaning limbs). The six limbs are described below in detail. Svatmarama emphasizes many times in his Hathapradipika text that there is no raja yoga without hatha yoga and no hatha yoga without raja yoga. The main difference is that raja yoga uses asanas mainly to get the body ready for prolonged meditation, and hence focuses more on the meditative asana poses: Lotus Posture (padmasana), Accomplished Posture (siddhasana), Easy Posture (sukhasana) and Pelvic Posture (vajrasana). Hatha yoga utilizes not only meditative postures but also cultural postures. Similarly, raja yoga's use of pranayama is also devoid of extensive locks (bandha).
Hatha represents opposing energies: hot and cold (fire and water, following similar concept as yin-yang), male and female, positive and negative. Hatha yoga attempts to balance mind and body via physical postures or "asanas", purification practices, controlled breathing, and the calming of the mind through relaxation and meditation. Asanas teach poise, balance and strength and are practiced to improve the body's physical health and clear the mind in preparation for meditation. However if an individual has too much phlegm or fat then purification procedures are a necessity before undertaking pranayama.
Ashtanga is the yoga of Patanjali, the compiler of the Yoga Sutras. It is composed of eight limbs: yama and niyama, which are ethical observations; asana; pranayama, which is breath control; pratyahara, which is sense withdrawal; dharana, which is concentration; dhyana, which is meditation; and samādhi, which is a high state of concentration, mastery of the mind. The eight limbs are more precisely viewed as eight levels of progress, each level providing benefits in and of itself and also laying the foundation for the higher levels. Frequently ashtanga yoga of Patanjali is being confused with raja yoga, Patanjali nowhere in his sutras uses the term raja yoga.
Hatha yoga consists of six limbs focused on attaining samādhi. In this scheme, the six limbs of hatha yoga are defined as asana, pranayama, pratyahara, dharana, dhyana and samādhi. The basic text of hatha yoga is Hathapradipika by Svatmarama, a grand disciple of Sahajananda (from the lineage of Sopana, the younger brother of Jnaneshwar Maharaj of Alandi near Pune). An important part of hatha practices is awakening of Kundalini. The signs of success in hatha yoga are slenderness of the body, cheerful face, hearing mystical sound, bright eyes, sense of well-being, control over the bindu, increase in gastric fire and purification of the nadis.