Asana can be defined as a physical Yoga posture or position that is designed to help master the body and enhance the body's functions.
Yoga poses are, in essence, Yoga exercises creating strength and endurance, improving circulation and energy flow, cleansing organs and other systems, and expanding muscles and joints. With all these benefits of the Yoga poses, we can not lose attention to the original purpose of the Yoga pose or Yoga exercise.
Yoga exercises evolved thousands of years ago from the need to create a healthy body in order to move more readily to the state of oneness and realization. When the body is cluttered with stress, tension, and disease, this clouds the mind and the ability to connect with the inner self. The physical freedom attained from the Yoga exercises increases one's ability to sit with silence and joyful observation.