Learning 2D Game Development with Unity®: A Hands-On Guide to Game Creation

Trigger Volumes in Unity

A trigger is a piece of invisible collision geometry that defines a space within a game area. Unlike normal collisions, triggers do not throw standard collision events and do not block GameObjects from passing through them. Rather, as objects pass through a trigger, events are raised in a script that you can hook into. Triggers are an extremely useful way to react to events occurring in specific locations within a Unity Scene.