Plantar fasciitis (PLAN-tur fas-e-I-tis) is one of the most common causes of heel pain. It involves inflammation of a thick band of tissue that runs across the bottom of your foot and connects your heel bone to your toes (plantar fascia).
Plantar fasciitis commonly causes stabbing pain that usually occurs with your first steps in the morning. As you get up and move, the pain normally decreases, but it might return after long periods of standing or when you stand up after sitting.
Plantar fasciitis is more common in runners. People who are overweight and those who wear shoes with inadequate support also have an increased risk of plantar fasciitis.
Plantar fasciitis typically causes a stabbing pain in the bottom of your foot near the heel. The pain is usually the worst with the first few steps after awakening, although it can also be triggered by long periods of standing or when you get up after sitting. The pain is usually worse after exercise, not during it.
Your plantar fascia is in the shape of a bowstring, supporting the arch of your foot and absorbing shock when you walk. If tension and stress on this bowstring become too great, small tears can occur in the fascia. Repeated stretching and tearing can irritate or inflame the fascia, although the cause remains unclear in many cases of plantar fasciitis.
Even though plantar fasciitis can develop without an obvious cause, some factors can increase your risk of developing this condition. They include:
Ignoring plantar fasciitis may result in chronic heel pain that hinders your regular activities. Changing the way you walk as a way to relieve plantar fasciitis pain might lead to foot, knee, hip or back problems.
Source: https://www.mayoclinic.org/diseases-conditions/plantar-fasciitis/symptoms-causes/syc-20354846