Quick answer
Apple’s photo-library synchronization service across devices using an account and the relevant settings.
Limitation
Synchronization is different from a separate archived copy. Changes and hidden status can propagate.
Related terms
Questions
What does iCloud Photos mean?
Apple’s photo-library synchronization service across devices using an account and the relevant settings.
What limitation matters?
Synchronization is different from a separate archived copy. Changes and hidden status can propagate.