iCloud is included with OS X. Once you sign up for your free iCloud account, you can push calendar updates across your devices, share your iCloud Calendar, and see your calendar on the iCloud website.

If you have an iCloud account , you can use iCal to access and manage your iCloud calendars. If you set up the iCloud Calendar service on several devices and computers, your iCloud calendar and reminder information is kept up to date on each device and computer.

Set up your iCloud calendar account from System Preferences to see your iCloud-based calendars in the Calendar window.