LOCKSCREEN
Lock screen
A lock screen is a user interface element used by various operating systems. They regulate immediate access to a device by requiring that the user perform a certain action in order to receive access: such as entering a password, using a certain button combination, or by performing a certain gesture using a device's touchscreen. While most lock functions on PC operating systems only utilize a login screen, lock screens on mobile devices often provide more functionality beyond unlocking the phone: such as notifications for emails and text messages, a date and time display, or shortcuts to certain applications.The above text is a snippet from Wikipedia: Lock screen
and as such is available under the Creative Commons Attribution/Share-Alike License.