What is iCloud Keychain?

iCloud Keychain is a feature for storing sensitive data securely online so that you can use it on your Mac and your iOS devices. iCloud Keychain can store passwords for Wi-Fi networks, numbers and expiry dates for credit and debit cards, and passwords for websites. With your permission, Macs and iOS devices can access data in iCloud Keychain and use that data automatically for you. For example, the Safari browser can automatically enter your payment details in an online shopping form.