Hatha yoga
Hatha yoga (Sanskrit  Template:IPA), also known as Hatha Vidya (), is a particular 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 'a stairway to the heights of Raja Yoga', hence a preparatory stage of physical purification that renders the body fit for the practice of 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 practise is called shatkarma. The word Hatha is a compound of the words Ha and Tha meaning sun and moon (     |   || ), referring to Praana and Apaana, and also to the principal nadis (energy channels) of the subtle body that must be fully operational to attain a state of dhyana or samadhi. According to the Monier Moneir-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 Raaja Yoga of Patanjali including moral restraint yama and spiritual observances niyama. Hatha Yoga is what most people in the West associate with the word "Yoga" and is practiced for mental and physical health throughout the West.

# Origins
The most comprehensive text of Hatha Yoga is the Hatha Yoga Pradipika by Yogi Swatmarama. This work is nonetheless derived from older Sanskrit texts on Yoga besides Yogi Swatmarama's own yogic experiences. It includes information about shatkarma, asana, pranayama, chakras, kundalini, bandhas, kriyas, shakti, nadis, and mudras among other topics.
Traditionally, Lord Shiva () is credited with propounding Hatha Yoga. It is said that on a lonely island, assuming nobody else would hear him, he gave the knowledge of Hatha Yoga to Goddess Parvati, but a fish heard the entire discourse, remaining still throughout. Lord Shiva took mercy on the fish (Matsya) and made him a Siddha, who came to be known as Matsyendranaatha. Matsyendranaatha taught Hatha Yoga to Chaurangi, a limbless man who was given hands and feet by Matsyendranaatha just by looking at him. Hatha Yoga Pradipika mentions Adinaatha, Matsyendranaatha, Gorakhanaatah and many other yogis who became famous Hatha Yogis.
Many modern schools of Hatha Yoga derive from the school of Sri Tirumalai Krishnamacharya, who taught from 1924 until his death in 1989.  Among his students prominent in popularizing Yoga in the West were Sri K. Pattabhi Jois, famous for popularizing the vigorous Ashtanga Vinyasa Yoga style, B.K.S. Iyengar who emphasizes alignment and the use of props, Indra Devi and Krishnamacharya's son T.K.V. Desikachar who developed the Viniyoga style. Desikachar founded the Krishnamacharya Yoga Mandiram in Chennai, with the aim of making available the heritage of yoga as taught by Krishnamacharya.
Another major stream of influence was Swami Sivananda of Rishikesh (1887-1963) and his many disciples, including Swami Vishnu-Devananda - founder of International Sivananda Yoga Vedanta Centres, Swami Satyananda - of the Bihar School of Yoga, and Swami Satchidananda - of Integral Yoga, among others.

# Concept
Traditional Hatha Yoga is a holistic yogic path, including moral disciplines, physical exercises (e.g., asanas (postures) and Pranayama (breath control)), and meditation. The Hatha yoga predominantly practiced in the West consists of mostly asanas (postures) and exercise.
Hatha Yoga is one of the two branches of Yoga that focus on the physical culture, the other one being Raja Yoga. Both of these are commonly referred to as Ashtanga Yoga, i.e., Yoga of eight parts ('ashta' meaning eight and 'anga' meaning limbs). The eight limbs are described below in detail. The main difference is that Raja Yoga uses asanas to mainly get the body ready for prolonged meditation, and hence focuses more on the meditative asana poses: Lotus Pose (Padmasana), Accomplished Pose (Siddhasana), Easy Pose (Sahajasana) and Pelvic Pose (Vajrasana); Hatha Yoga utilizes most of the asana poses. 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 the same concept as the yin-yang), male and female, positive and negative. Hatha yoga attempts to balance mind and body via physical exercises, or "asanas", controlled breathing, and the calming of the mind through relaxation and meditation. Asanas teach poise, balance & strength and are practiced to improve the body's physical health and clear the mind in preparation for meditation in the pursuit of enlightenment.
The Yoga of Patanjali is Ashtanga or composed of 8 limbs, Yama and Niyama, which are ethical obligations, Asana, Pranayama, which is breath control, Pratyahara, which is sense withdrawal, Dharana, which is concentration, Dhyana, which is meditation, and Samadhi, which is the experience of unity with God.. 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.
NOTE: In some schools of thought, only Raja Yoga is considered to be Ashtanga Yoga, and Hatha Yoga is thought to consist of six limbs focused on attaining Kundalini. In this scheme, the six limbs of Hatha Yoga are defined as Yama, Niyama, Asana, Pranayama, Mudra (specific postures to help lock in the breath), Nadanusandhana (hearing of the eternal sound within the body), the whole process culminating in the attainment of Kundalini. Due to this, this version of Hatha yoga is also sometimes referred to as Kundalini Yoga.

# Yama and niyama
Yama is a "moral restraint" or rule for living virtuously. Ten yamas are codified in numerous scriptures, including the Hatha Yoga Pradipika compiled by Yogi Swatmarama, while Patanjali lists five yamas, and five niyamas (disciplines) in the Yoga Sutra.
The ten traditional yamas are: 
- Ahimsa: Nonviolence. Abstinence from injury, or harm to any living creature in thought, word, or deed. This is the "main" Yama. The other nine are there in support of its accomplishment.
- Satya: Truthfulness in word and thought (in conformity with the facts).
- Asteya: No stealing, no coveting, no entering into debt.
- Brahmacharya: Divine conduct, continence, celibate when single, faithful when married.
- Kshama: Patience, releasing time, functioning in the now.
- Dhriti: Steadfastness, overcoming non-perseverance, fear, and indecision; seeing each task through to completion.
- Daya: Compassion; conquering callous, cruel and insensitive feelings toward all beings.
- Arjava: Honesty, straightforwardness, renouncing deception and wrongdoing.
- Mitahara: Moderate appetite, neither eating too much nor too little; nor consuming meat, fish, shellfish, fowl or eggs.
- Shaucha: Purity, avoidance of impurity in body, mind and speech.
Patanjali's five yamas, or moral restraints, are ahimsa (non-injury), satya (truthfulness), asteya (non-stealing), brahmacharya (continence or chastity) and aparagriha (abstinence from avarice).  He also lists five niyamas, or disciplines, which include shauca (purity), samtosha (contentment), tapas (asceticism), svadhyaya (study), and ishvara-pranidhana (devotion to the Lord). 

# Asanas (Postures)
Asanas are contemplative in nature and were originally intuited by yogis during meditation; the Kundalini naturally brings forth these postures or movements, called Kriyas, during deep meditation.  These movements are meant to help to remove blockages (disease) in the causal, subtle, and physical bodies.
In the ancient author Patanjali's work, Asana is classified as the third rung of 8 in the ladder of the practice of Raja Yoga.
Hatha yoga in the west primarily concerns itself with asanas or postures.

# Pranayama (Breathing)
The words 'Prana' (life-force) and 'Ayama' (to lengthen or regulate) make up Pranayama. Pranayama seeks to lengthen, control & regulate the breath. In one variation, the Rechak (exhaled air), 
Poorak (inhalation) and Kumbhak (Retention during normal inhaling and exhaling) are the 3 parts of the breath that are regulated. Pranayama is practiced to develop mental, physical and spiritual strength. Though the beginner's Pranayama is relatively harmless, safely progressing to more advanced practices requires the guidance of a knowledgeable teacher.

# Health Benefits ascribed to Yogasana practice
Different asanas are recommended by practitioners to cure or prevent problems ranging from constipation to cancer. It is known to reduce stress and other mental worries.
See Yoga (alternative medicine)

# Etymology
Hatha yoga, pronounced Template:IPA, is also known as hatha vidya or the "science of hatha" yoga. The word Hatha comes from combining the two Sanskrit terms "ha" meaning sun and "tha" meaning moon. The word "ha" refers to the solar  nadi (pingala) in the subtle body and "tha" the lunar channel (ida).  However, when the two components of the word are placed together, "hatha" means "forceful", implying that powerful work must be done to purify the body. Yoga to means to yoke, or to join 2 things together, hence hatha yoga is meant to join together our sun (masculine, active) energy with our moon (feminine, receptive) energy, thus producing balance and greater power in an individual.

# In the West
The 2005 "Yoga in America" survey, conducted by Yoga Journal, shows that the number of practitioners in the US increased to 16.5 million with the 18-24 age group showing a 46% increase in one year.