Plantar fasciitis is a painful inflammatory condition of the foot caused by excessive wear to the plantar fascia that supports the arch or by biomechanical faults that cause abnormal pronation.
The pain usually is felt on the underside of the heel, and is often most intense with the first steps of the day. It is commonly associated with long periods of weight bearing or sudden changes in weight bearing or activity. Obesity, weight gain, jobs that require a lot of walking on hard surfaces, shoes with little or no arch support, and inactivity are also associated with the condition.
Read more about this at the source here – http://en.wikipedia.org/wiki/Plantar_fasciitis
Or download the fact sheet below on “Heel Pain” from the Australasian Podiatry Council.