It is the most common cause of pain to the heel and bottom of the foot.The plantar fascia (a ligament on the bottom of the foot extending from the heel to the toes) becomes inflamed and painful. This condition is most often caused by a tight Achilles tendon limiting the ankle motion and causing the foot to stress the plantar fascia with every step. It can also be caused by poor foot structure such as overly flat feet or high arches, by wearing non-supportive footwear on hard surfaces, spending long hours on your feet, or obesity (at least 3- 4 times your body weight passes through your foot with each step). The pain from plantar fasciitis is usually a sharp, stabbing pain on the inside of the bottom of the heel that can feel like a knife sticking into your heel. Pain from plantar fasciitis is usually most severe when you first stand on your feet in the morning. It will usually subside, but can return with prolonged standing or walking or getting up after long periods of sitting or after sleeping. As the pain progresses, it may become increasingly painful to the entire heel or may cause other pains as you walk differently (for example knee, hip or back pain may be caused initially by this heel pain). The good news with plantar fasciitis, however, is that it can and should be treated.