If you have a Gmail account then this is the easiest way of having your bookings automatically appear in your calendar. Whenever a booking is created, amended or deleted it will be entered into your calendar.
If you have not yet enabled Google Calendar Integration this page will display a link for you to enable it, you will then be taken to Google where you can authorize the integration. You will not need to disclosure any personal details and you can disable the authorization at any time.
If you have already enabled integration this page will display that it is enabled and provide a link to disable it. You can also disable it by going into settings on your google home page.
You are in total control of this and can switch it on and off at any time. You also do not need to reveal your Google password or any other personal details.
Enabling integration will not synchronize existing bookings.