Plantar fasciitis (say "PLAN-ter fash-ee-EYE-tus") is pain in your heel or the bottom of your foot. It happens when the flat band of tissue (ligament) that supports the arch of your foot is inflamed or irritated.
Plantar fasciitis is common in middle-aged people. It also occurs in younger people who are on their feet a lot, like athletes or soldiers. It can happen in one foot or both feet.