A hoplite was a citizen-soldier of the Ancient Greek city-states. A hoplite's main weapon was his spear. They fought close together in what was called a phalanx formation. In a phalanx, each man's shield protected himself and also gave some protection to the right arm of the man on his left.
The word "hoplite" comes from the type of the shield used by the soldiers. In later texts, the term hoplite is used to denote any armoured infantry, regardless of armament or ethnicity.