Yog (widely used as Yoga) is originated from Sanskirt (the language of ancient Himalayas) where “Yuj" meaning to yoke, join or unite or union. Yoga is a union occurring between the mind, body and spirit. This implies joining or integrating all aspects of the individual - body with mind and mind with soul - to achieve a happy, balanced and useful life, and spiritually, uniting the individual with the supreme. Yoga can be more accurately described by the Sanskrit word asana, which refers to the practice of physical postures or poses.
Asana is only one of the eight "limbs" of yoga, the majority of which are more concerned with mental and spiritual well being than physical activity. In the West, however, the words asana and yoga are often used interchangeably.
Yoga is considered one of the six branches of classical philosophy and is referred to throughout the Vedas - ancient Hindu scriptures and amongst the oldest texts in existence. The Upanishads are also broadly philosophical treatises which postdate the Vedas and deal with the nature of the "soul" and universe. However, the origins of yoga are believed to be much older than that, stemming from the oral traditions of Yogis, where knowledge of Yoga was handed down from Guru (spiritual teacher) to Sisya (spiritual student) all the way back to the originators of Yoga, "the Rishis," who first began