Triggers

Triggers are colliders used to detect other colliders enter it, which you can use to script events. For example, you can detect when a player character enters a room, and use this in your script to trigger an event.

Triggers don't generate collisions.

Note

Triangle Mesh colliders cannot be triggers.

Create a trigger

Create a Colldier (box, sphere, etc.)
Check Is Trigger

Use a trigger

Triggers use dedicated trigger events that you can register for:

Trigger.TriggerEnter
Trigger.TriggerExit

To learn more about using triggers see tutorial How to use a trigger.