Asana is yoga pose or posture or position of the body. Patanjali in ashtanga yoga defines asanas as Steady and Comfortable pose.
A healthy and peaceful body is the starting point for advance practices. This is the purpose of Asanas.
Benefits of Asanas or Yoga poses - make the body healthy and strong and to make the mind peaceful and focused.
In Asanas, body is subjected to different stretches, bends, twists, inversions and strains. Then you try to maintain the posture in a relaxed manner. This practice builds the strength and stamina. Especially various muscles are strengthened, which is the support for all other systems. Functioning & efficiency of the internal organs is improved. This affects all other parts of the body in positive manner.
In asanas, you try and connect the mind to the body. You try increasing the awareness of body parts, focusing on stressed joints and muscles, maintaining awareness of the breathing. One needs a lot of skill in trying to relax the muscles and different parts under stress during asana practice. This is strengthening of Body- Mind relationship.
Other benefits of the Yoga poses include increasing flexibility, stamina, and endurance of various body parts. Asanas or yoga poses or yoga positions increase efficiency of digestive system, and various digestive organs such as liver, pancreas, stomach, intestines. Yoga poses increase the efficiency of respiratory system and makes it more efficient promoting abdominal and relaxed breathing. Asanas also have positive effect on reproductive system, excretory system.