Each Calendar user is associated with a primary calendar and a
number of other calendars that they can also access. Users can create events and
invite other users, as shown in the following diagram:

![Simple model of calendars and events](https://developers.google.com/static/workspace/calendar/api/images/users-calendars.png)

This example shows two users, Susan A and Wei X. Each has a primary calendar and
several other associated calendars. The example also shows two events: an
end-of-year presentation and a team offsite.

Here are some facts shown in the diagram:

- Susan's calendar list includes her primary calendar as well as calendars for
  her team and cello lessons.

- Wei's calendar list includes his primary calendar as well as the team
  calendar, a status tracking calendar, and Susan's primary calendar.

- The end-of-year presentation event shows Susan as the organizer and Wei as an
  attendee.

- The team offsite in Hawaii event has the team calendar as an organizer
  (meaning it was created in that calendar) and copied to Susan and Wei as
  attendees.

These concepts---calendars, events, attendees, and others---are explained in
detail in the following sections of this guide:

- [Calendars and events](https://developers.google.com/workspace/calendar/api/concepts/events-calendars)
- [Calendar sharing](https://developers.google.com/workspace/calendar/api/concepts/sharing)
- [Invite users to an event](https://developers.google.com/workspace/calendar/api/concepts/inviting-attendees-to-events)
- [Reminders and notifications](https://developers.google.com/workspace/calendar/api/concepts/reminders)
- [Domain resources, rooms, and calendars](https://developers.google.com/workspace/calendar/api/concepts/domain)