Apple has added a two-step verification feature for your Apple ID. It is an optional security measure that requires users to verify their identity using a device before they can sign into Apple ID to manage account. Also you would have to follow the two-step verification in order to make iTunes, App Store, or iBookstore purchase from a new device and get Apple ID-related support from Apple. Turning on the two-step verification reduces the possibility of unauthorized changes to users accounts.
