You can attach an Event to Opportunities in one of two ways:

• Add the appropriate event in the Add to Event field on the opportunity, OR
• Add the appropriate opportunity to the Opportunities tab of the event.

When an Event is added to an Opportunity, two things happen:

1. If the Event is viewable on the Event Calendar page, a "Volunteer" button displays, which directs the user to the Opportunity page and allows them to respond.
2. When any Response record related to the Opportunity is updated as "Placed", the related participant is added to the event.