Abstract: A method of controlling a display device is provided, in which the method includes providing an entry mode to determine an entry into an adult mode or a child mode through a child indentifying interface including a visual object, recognizing a user input in response to the visual object, and providing the adult mode or the child mode based on a degree of similarity between the recognized user input and the visual object, wherein the child mode may be a mode providing a selecting interface to select at least one application and a time limit interface to terminate the application after executing, for a preset period of time, the application selected through the selecting interface.