Enabling iCloud Photos on your iPhone or iPad device
By enabling iCloud Photos, you enable your device to function as an “Unlimited Memory” device, offloading excess data into iCloud.
iCloud Photo Library automatically keeps every photo and video you take in iCloud, so you can access your library from any device, anytime you want. Any changes you make to your collection on one device, change on your other devices too. Your photos and videos stay organized into Moments, Collections, and Years. And all of your Memories are updated everywhere. That way you can quickly find the moment you're looking for anywhere you go. Your collection uploads to iCloud each time your device connects to Wi-Fi and your battery is charged. Depending on your Internet speed, the time it takes for you to see your photos and videos on all of your devices and iCloud.com might vary.
For the best experience, also sign in to iCloud on your Mac or Windows PC in addition to your iPhone and iPad.
To get started, first:
Next, on all of the iPhones and iPads that share the same Apple ID, do the following:
All Done! You can verify that the uploads are taking place by plugging your device into power, then opening Photos and scrolling to the bottom of the thumbnails. You should see a screen similar to below:
If you need additional help with iCloud Photos, please visit this Help Article on Apple.com.