A hoplite is a particular kind of Greek heavy infantry soldier. For armor, Hoplites had a bronze helmet, breastplate, and greaves. They carried a huge round shield (I don't know if it was bronze or wood or both) that went from their chin to their knees. Their primary weapon was a long spear which has an official name that I will put here when I dig up my notes. The spear was about 15' long. The other nifty thing about them is that they operated in a phalanx, a formation in which the front three to five rows of men all lowered their spears, and the rear-most lowered spears stuck out in front of the front row. Quite a defense.
The idea of Hoplites came along around the same time that Persia was making use of cavalry (without stirrups at the time), around 500 BC. When Persia invaded Greece, the Hoplites proved superior to the poorly trained light infantry conscripts and the light cav of the Persians, to the point that the Greeks were winning battles in which they were outnumbered four to one (I think). The other reason the Greeks drove back the Persians was because of their superior navy made up of triremes.