Missing an appointment or an event because you forgot to add it to your calendar is never a fun experience. Although, it does make for a good excuse. If you and your significant other (or coworkers, for that matter) use an iOS device, a Mac, iCloud, or any combination of the sort you can easily share an iCloud calendar, making sure you are both on the same schedule.
Sending an invite to share an iCloud calendar using your iOS device takes just a few taps. Share an existing calendar, or create a new one, and share it by entering an e-mail address. Just make sure your device is running iOS 5 and above.
Using a Mac to send shared calendar invites may be the easiest method of the three. Click on an icon, type in an e-mail address, and click done. Nothing more to it than that. If you want to change a person's access to a calendar, it's just as easy to edit. Read the full post for a complete walkthrough.
iCloud.com is the least convenient method, but it still works. You'll need to be at a computer; using your favorite browser, visit iCloud.com. From there, you'll only need an e-mail address for the person (or people) you want to share the calendar with.
The key to sharing an iCloud calendar is that anyone who is invited has to have an iCloud account. If the individual you want to share an iCloud calendar with doesn't have an iCloud account, you can make the calendar public and provide them with a link to subscribe to the calendar. But keep in mind that he or she will be unable to add or edit any information on the shared calendar.