What is iCloud?
Photos
For many of us, Photos is the killer app of iCloud. By storing all our images and videos in the cloud it doesn’t matter what device we’re using when we want to look at or edit our photos and movies — they’re available on our Macs, iPhones, iPads, and Apple TVs. It can make sure your photos don’t take up too much room on any device, and it also enables you to quickly and easily share your photos with your friends and family.
Two–factor authentication
Your various iCloud services use the familiar Apple ID and password, but for even better security you can set up two– factor authentication. This adds an extra layer of security that makes it much harder for various villains to get into your iCloud account. Apple also enables you to set up app–specific passwords, which are unique one–off passwords for apps or online services that want to use your iCloud data.