This document discusses insertional and noninsertional Achilles tendonitis. It begins by covering the etiology, pathophysiology, and classification of the conditions. Histopathologically, it can present as paratenonitis, paratenonitis with tendinosis, or tendinosis. Symptoms include pain, swelling, and impaired performance. Nonsurgical treatments discussed include rest, bracing, exercises, shockwave therapy, and various injections. Surgical management is considered for recalcitrant cases and involves debriding degenerative tissue and potentially augmenting the tendon with a transfer. Post-operative rehabilitation protocols are also outlined.