You can share a fully editable calendar via iCloud with other people in your family or at work, school, or in groups so you can have a collective place to coordinate appointments and share information about them. But that’s a two-edged sword: if someone else can edit a calendar you’re sharing, they can–usually unintentionally–delete or modify events.
My family shares multiple calendars among ourselves, including ones my spouse and I share with each other for work and personal scheduling. The other day, I got a text from my partner: “Why did you modify this event of mine?” about an appointment that was solely hers. Me: “I didn’t! Oh, I was trying to drag to add an event on my calendar, and I kept grabbing that one. But I used Undo!” She received a notification that it was modified, nonetheless.
Read more at Macworld.com