You can import calendars from other websites that support the iCal format like Google. iCalendar is a file format that allows users to create and share electronic calendars. The iCalendar format is supported by many companies and programs.
Importing enables you to have a single-calendar view of all your reservations, seasonal events, holidays and more. This will help you prevent a double booking. It also helps you see opportunities to adjust your rates to make more money.