Achilles tendinitis is an overuse injury that affects the Achilles tendon, the band of tissue connecting the calf muscles to the heel bone. It commonly occurs in runners or athletes who suddenly increase the intensity or duration of their activity. The condition causes pain, stiffness, and swelling in the back of the heel, especially during physical activity or after periods of rest. There are two main types: non-insertional, which involves small tears in the middle portion of the tendon, and insertional, which affects the point where the tendon attaches to the heel bone. Risk factors include tight calf muscles, poor footwear, and training on hard surfaces. Early treatment includes rest, ice, stretching, and anti-inflammatory medications. More severe cases may require physical therapy or, rarely, surgery. Proper warm-up, strengthening exercises, and gradual increases in training intensity can help prevent Achilles tendinitis and reduce the risk of re-injury