Yoga has its origin in India. It was widely practised during the Vedic period (about 1900 to 600 BC). The codification of all yoga literature was done by Patanjali.
There are many schools of yoga. The most famous great yoga systems are Hatha Yoga, Raja Yoga, Kundalini Yoga and Mantra Yoga. Besides these four systems, there are various others.
In ancient times ascetics left their homes and wandered to distant places especially in the Himalaya area where they lived alone as hermits or holy men to practise yoga in the hope of liberating themselves from the attachments of the body, mind and soul. After many many years of hard work, some achieved results of various degree and possessed superhuman or occult powers. They were called Yogis and could lie on beds of nails, remain buried underground, withstood very cold weather conditions, etc.
Yoga can help the practitioners to reduce or maybe eradicate stress resulted from modern day life styles. The constant practise of its physical exercises which are called asanas with the combination of breathing exercises called pranayamas will benefit a person in the long run. It not only relaxes one physically but also mentally.
With the advancement in these modern times, the practice of yoga and the objective in learning it are very much different from that of previous years. Commercialisation has taken place. Even its exercises maybe combine with elements from other physical exercises from systems revolutionalised long after the existence of yoga. But anyway modern day practice of yoga will still benefit its practitioners.