Caller ID is all or nothing. Either everyone gets to see your number when you call, or you block it and nobody sees it.
It's Me changes that. Now you can show your Caller ID to just the people you want to know it's you.
Start by turning Caller ID off in your iPhone settings. This blocks your number from being visible to just anyone. Then open It's Me. It's Me shows you your contacts and lets you unblock your Caller ID to the ones you choose. And only the ones you choose.
Keep your privacy with strangers, but don't lose your intimacy with friends. Let them know it's you - with It's Me.