A troop in RPG Maker is a set group of enemies that can be set to be encountered in a battle. Enemy troops can be encountered by random chance on a map when moving across it, or triggered by an event. Maps and events cannot be configured to trigger a battle with a certain enemy that is not part of a troop, but troops can be configured to have a single enemy in them. Troops can consist of one to eight enemies, and each one can be of a different kind.
Using events to fire battles with troops is useful for on screen encounters. Using event commands, a developer can choose to make a battle start when a specified on screen enemy is touched.