The Roman gladiators, whose name comes from the antique Roman sword "gladius", were for the main part war prisoners, slaves or persons sentenced to death. To the spectacles, however, were participating only free men attracted by the rewards and glory, but whoever decided to become gladiator was automatically considered "infamis" for the law.

We suppose that the gladiator spectacles found their origin in the far back mortuary ceremonies celebrated with the human sacrifice to calm the rage of the hellish Gods and the anxiety of the dead. The fighters were following a hard training in the schools founded by Nerone and Cesare in which they were exposed to tortures and a established order with the repetitive use of restraints with fire and whip. The discipline was hard, with unbending rules and with severe punishments in such a way to have the gladiators become real fighting machines.
At the end of the training period all the fighters were grouped in "companies" of exclusive ownership of the Imperator.
The challenges were starting by a parade where the gladiators were making their stage entrance on chariots or by foot followed by a group of drummers; once they had reached the podium of the Imperator, they were greeting him with the words "Ave cesare morituri te salutant" ("Ave o Cesare, those who are about to die are greeting you"), then they were going towards the organizer of the games who examined the weapons which were different on the base of the category of the fighter.
The "retiarii", inspired by the God Triton, were fighting half nude armed of a net, a trident and a knife; the "mirmilloni" however had a helmet, a shield and were armed of a sickle, the gladiators, who were part of the category of the "sanniti" were wearing a helmet equipped of crests, a strong armour and were grasping a javelin. The duellists who were chosen were belonging to diverse categories in such a way to make the spectacle more compelling; from some chronicles of the time, in fact, it even seems that the Imperator Nerone, to honour the king of Armenia, Tiridate, made a dwarf fight against a woman.
Sometimes the attacks, after having rendered the arms inoffensive, were only simulated but in the main part of the cases the fights were hard and bloody and were ending by the death of one of the gladiators. If the defeated was wounded he could ask for grace by raising the arm, therefore the public was asking for salvation or death with the authority present on the imperial podium, by showing the inch facing downwards, or waving a white handkerchief. The fighters killed, before they were taken away, were approached by two slaves dressed as Caronte and Ermete Psicopompo: one was checking the death by touching with a hot piece of iron, the other, eventually, was giving them the final stroke making then the sign to the "libitinarii" to take the body away dragging it on the arena with a hook.
The winners were rewarded with gold palms, money and the immense popularity won above all among women; if the winning gladiator was a slave, after ten victories, which were written on a metallic collar, he was granted back liberty; he could therefore decide if continuing to fight for money or starting other activities such as for example the instructor in the schools for gladiators.
Another game very appreciated by the public was the "venationes" where the gladiators were fighting against ferocious animals such as elephants, hippopotami, lions, bulls, tigers, panthers, and leopards. The hunts could also consist in a challenge between one or more animals contemporaneously, or they could also be a pretext for executions, when the sentenced persons were introduced in the arena without any defence together with the wild beasts.
The "naumachie" were also very appreciated, that consisted in false naval battles, but as they cost a lot in expenses relative to the armament of the ships, they were rarely organized. From time to time were participating, also if the law was forbidding it, women and members of the upper classes, but obviously they were not mixed with the other gladiators and were not fighting up to death.