Asanas — the word asana literately means "a posture". Every posture the body can take is an asana. Certain postures are possibilities for elevating human consciousness.
Yogasanas are not exercises, this must be clearly understood. They are subtle processes to direct and activate our energy in the particular direction, to bring us to a state where we are a cosmos by our self. Practicing Yogasanas brings awareness, brings sense of freedom and prepares a person to the higher level of consciousness.