A spun-off product formerly integrated with Google+, Google Photos is a photo backup and viewer service by Google that comes with build in photo editor interface.
Pro Smart shared libraries
Google Photos allows inviting other users to shared libraries. It has a feature that allows auto-adding all photos and videos or only of specific people to the shared library which is really useful for sharing with families or a close group of friends. It also allows the invitee to save those photos straight to their device automatically as if they took it.