Official definition- an ancient martial art which mixes wrestling and boxing.
Its name derives from the Ancient Greek words pan (all) and kratos (strength, might, power) and means "all of the might"
Rules- It was a dangerous sport, in which everything was permitted except biting, gouging (stabbing you finger in your opponent's eye, nose or mouth).
How the sport is similar to today- the sport is similar to boxing today. Except the sport has calmed down a little bit. You do not go to a boxing match and see them stabbing each other's eyes!