The iCloud Photo Library synchronizes your iPhone photos by automatically uploading the photos you click to iCloud. Once they are uploaded or backed up to iCloud, you can then view the photos across all your devices that have the feature turned on. For example, if you a device where the feature is turned off, you will not be able to see your photos uploads on that device. In order to turn On iCloud Photo Library on your iPhone, follow the process below:
- Open the iPhone's Settings app.
- On the menu, scroll down and tap "iCloud".
- In the iCloud settings, choose "Photos".
- The option to turn on iCloud Photo Library will be at the top of the screen.
- The "Optimize iPhone Storage" option will download thumbnail versions of the photos when the iPhone is low on space.
- The "Upload to My Photo Stream" option will synchronize the full images across devices with this option turned on. This is useful if you need access to the photos even when you don't have an Internet connection.
- If you would like to create custom photo albums to share with a group of friends, you should turn on "iCloud Photo Sharing". This lets you created shared photo albums and invite friends to view the photos.