An exoskeleton ("exo" = external) is a supporting apparatus which is on the outside of the body, in contrast to an internal skeletal structure. We know of the natural version from crabs, insects, and other arthropods and artificial exoskeletons have been featured in science fiction and action films. In movies, these exoskeletons are imagined to be fighting machines that turn ordinary beings into invincible super heros. However, artificial exoskeletons have long since existed in reality, in different forms and for different purposes. They can provide assistance in cases where natural muscle power is inadequate, e.g. for lifting heavy components or working overhead with a bulky grinding machine for long periods. People with paraplegia can walk again with an exoskeleton, as was demonstrated in Brazil at the kick-off to the opening game of the football World Cup in 2014.