Photo Stream is a feature available to iCloud users: It automatically syncs images you take across all your devices. That means the picture you took on your iPhone at the beach will automatically be viewable on your iPad, no cords or syncing required. On iOS devices, Photo Stream will save either your 1000 most recent pictures or the last 30 days' worth of images, whichever is greatest. All you have to do is enable Photo Stream on all your devices. The best part? It doesn't even use your iCloud storage!
How to enable or disable Photo Stream on your iPhone or iPad
Launch the Settings app on your iPhone or iPad.
Tap Photos & Camera.
Turn On or Off the option for Upload to My Photo Stream.
You can also find the same option to turn Photo Stream on or off under Settings > iCloud > Photos. Keep in mind that if you're disabling Photo Stream, the photos currently in your Photo Stream will be removed from that particular device. This is an ideal option if you don't want your photos going to a shared device that is tied to your iCloud account.
It's also good to remember that there are differences between iCloud Photo Library and your Photo Stream. Disabling Photo Streams won't disable iCloud Photo Library, and vice versa. If you have iCloud Photo Library enabled, you won't see a separate section for your Photo Stream in the Photos app, as all your photos are uploaded to the cloud (and they do count toward your iCloud storage space). Photo Streams, on the other hand, are still subject to the 1,000 photo limit or most recent 30 days rule, and are separate from your Camera Roll. If you want to learn more about either, you can do so via the links below.