How private is your information when Family Sharing?

Apple ID accounts are personal and individual, and should not be shared.

Apple offers Family Sharing as a method to share select services, by forming a group of Apple IDs (users). Only the service itself is shared, not the content use details. Privacy is important, and is limited to what is needed. As much as possible, any usage of the shared services is separated by Apple ID account, unless otherwise noted (e.g. optional location sharing).

Family Sharing does not disclose your photos (unless you choose to share an album) or messages, or other activities. Family Sharing does not share your watch history or music playlists, although you may choose to share a playlist.

Family Sharing can set limits for child accounts.

The Purchase Sharing option (which the organizer can set) may share purchases [buy items, like movies or ebooks] with the group members.

What plan(s) [services] are you considering for sharing?

To follow up on varjak paw's excellent advice:

Navigation here is a little tough until you use the forums for a while. That learning curve can be greatly reduced by bookmarking this forum site map:

Site Map - Apple Community

Note there is a section expressly for Apple ID questions.

Also, for future questions you may have, this forum (the "Using the Community" forum, where you originally posted) is for questions about the communities themselves. You'll usually be more likely to get useful advice if you post in the forum specifically for your device or operating system.

Regards.