Triathlon is a combination of swimming, cycling and running with athletes competing to achieve the fastest time across all three elements.
Athletes compete in six classes based on the nature and extent of their impairment. In the seated class (PTWC), athletes use a handcycle for the cycling element of the competition and a wheelchair for the running element. In standing classes (PTS2-5), they may use assistive devices, such as prosthetic legs, and bicycle modifications are also permitted. In the visual impairment class (PTVI), athletes are assisted by a guide of the same sex throughout the competition. After Rio 2016 the classification was further divided from six to nine. The classes are summarised below: