Plantar fasciitis is one of the most common causes of heel pain. It occurs when the plantar fascia—the thick band of tissue that supports the arch of the foot—becomes irritated or overloaded. Symptoms often include sharp pain with the first steps in the morning, after sitting for long periods, or following prolonged standing and walking. A healthcare professional can usually diagnose plantar fasciitis through a medical history and physical examination without the need for imaging.