by yoga meditator
Bikram Yoga, also known as Hot Yoga was created and developed by Bikram Choudhury, the self-proclaimed Yogi to the Stars. Bikram Yoga is practiced in a room heated to 105°F (40.5°C) with a humidity of 40%. The students are guided with dialogue whilst posing in 26 unique postures complete with two breathing exercises. Each class last about hour an a half. It is a beginners course, so everyone practices together.
Hatha Yoga is a particular system of Yoga described by Yogi Swatmarama, a yogic sage of the 15th century in India, and compiler of the Hatha Yoga Pradipika. Hatha Yoga is a development of -- but also differs substantially from -- the Raja Yoga of Patanjali, in that it focuses on shatkarma, the purification of the physical as leading to the purification of the mind (ha), and prana, or vital energy (tha). In contrast, the Raja Yoga posited by Patanjali begins with a purification of the mind (yamas) and spirit (niyamas), then comes to the body via asana (body postures) and pranayama (breath). Hatha yoga contains substantial tantric influence, and marks the first point at which chakras and kundalini were introduced into the yogic canon. Compared to the seated asanas of Patanjali's Raja yoga which were seen largely as a means of preparing for meditation, it also marks the development of asanas as full body 'postures' in the modern sense.
Hatha Yoga in its many modern variations is the style that most people actually associate with the word "Yoga" today. Because its emphasis is on the body through asana and pranayama practice, many western students are satisfied with the physical health and vitality it develops and are not interested in the other six limbs of the complete Hatha yoga teaching, or with the even older Raja Yoga tradition it is based on.
Meditation, relaxation and spiritual exploration... http://www.meditationinformation.info/hatha/types-of-yoga/bikram-yoga.html