Posture is the position in which you hold your body upright against gravity whilst standing, sitting or lying down. Good posture involves training your body to stand, walk, sit and lie in positions where the least strain is placed on supporting muscles and ligaments during movement or weight-bearing activities.
Good posture helps with the following:
keeping bones and joints in the correct alignment so that muscles are used properly.
decrease the abnormal wear of joint surfaces that could result in arthritis.
prevents the spine from becoming fixed in abnormal positions (eg scoliosis, kyphosis and lordosis).
Prevents fatigues because muscles are being used more efficiently