Types of gladiators (in ancient Rome):
bestiarii: Specialized in killing animals
retiarii: Fought with a net and dagger
essedarii: Fought from chariots
equites: Fought from horseback
hoplomachi: Heavily armed
The Thrax, or Thracian: Lightly armed w/ a small dagger (sica)
The A.M. of a spectacle (at the Colosseum) was for beast hunts; the early afternoon to tryouts, mock battles, or criminal execution; later afternoon for the main event, when the gladiators would fight in pairs until one could not continue, at which point the winner would ask the sponsor (munerarius) whether he should spare or kill. Pollice presso, basically, thumb down, to spare; pollice verso, thumb turned, to kill.
Gladiatores first appeared in Rome in 264 B.C., and only at funerals or for games given for an individual (in memoriam). The gladiators could be condemned criminals, prisoners of war, slaves, or volunteers (auctorati, bound over - their pay was termed auctoramentum). There were four training schools for gladiators (after Dominitian's time). Each school had its own fighting style and master.
Once the gladiators were in the amphitheater they began with a preliminary fight (prolusio) using swords and darts, until the trumpet blew and the main fight began (accompanied by music). Some gladiators were prodded with red-hot irons. The sign of mercy (missio) was the waving of handkerchiefs.
Condemned criminals had no chance of mercy in a fight. The FELLED were taken through a door (porta Libitinensis) into a side room (spoliarium) to be stripped and likely put to death. Victors received palms and sometimes money. A gladiator could, by long-term bravery, have the favor of the spectators. In such cases, he was given a rapier (rudis) that deemed him free of further toil. A freed gladiator was called rudiarius (which did not mean absolutely free).
In Pompeii there is a preserved gladiator school and a large bas-relief of gladiatorial combat.