The Achilles tendon is the strongest and largest tendon in the body. It is the conjoined tendon of the gastrocnemius and the soleus muscles, and may have a small contribution from the plantaris. The muscles and the Achilles tendon are in the posterior, superficial compartment of the calf. Through the Achilles tendon, they are the main plantar flexors of the ankle. The Achilles tendon is subjected to the highest loads in the body, with tensile loads up to ten times body weight during running, jumping, hopping, and skipping. This article discusses the anatomy of the Achilles tendon.