iCloud: Photos overview
iCloud Photo Library beta
iCloud Photo Sharing
My Photo Stream
iCloud Photo Library beta automatically stores every photo and video you take and gives you access to your entire photo library on your iPhone, iPad, iPod Touch, and on iCloud.com.
iCloud Photo Sharing lets you share your favorite moments with just the people you choose. Friends and family you invite to share your albums can post their own photos, videos, and comments, and changes appear automatically on everyone’s devices.
iCloud also updates your recently added photos across your devices with My Photo Stream. It’s a convenient way to save your latest photos to devices where iCloud Photo Library beta is not enabled.