Introduced with Yosemite and iOS 8 is Family Sharing. Family Sharing allows up to six members of one family to share music, movies, books, apps, photos, calendars and more.
It’s fairly straight forward to set up: one member takes the lead – and by doing so agrees to pay for everything! – and invites other family members to join. This feature is particularly advantageous for people who purchase lots of music or movies through iTunes. If you and your kids, or your significant other have purchase music using your individual iTunes accounts, I’m sure you’ve notice that there is no way to share music. Family Sharing solves this problem by allowing all of you to share your purchased items from the iTunes store.
There is another rarely mentioned benefit to this new feature, at least, for some of you. I have had quit a few clients who by accident, over time, set up multiple iTunes accounts (multiple Apple IDs.) This has lead to the problem of owning music, books or movies purchased under different accounts. However, if you are logged into to one account you cannot play music, movies or read books purchased under the second account. There is no easy way to combine two accounts into one. However, you can treat a second account as a family member thereby allowing your two accounts to share purchases. Problem solved.