The feature, called two-step authentication, provides an added layer of protection against hackers. With two-step authentication enabled, logging into your iCloud account from a new device requires your phone to be with you. Apple will text you a temporary numerical code, which you will need in addition to your Apple ID and password to get in.
Apple recently expanded two-step authentication to include many of its services. However, as of last month, it still didn’t guard iMessage and FaceTime.
That meant that, even if you enabled this security feature, anyone who guessed your password could still see your iMessage conversations or impersonate you on that chatting platform. More