A display device comprising: a display unit; a user input interface configured to receive a signal from a remote control device; and a controller configured to: - when a function key setup mode entry signal is received from the remote control device, display images of a plurality of keys of the remote control device on the display unit, the plurality of keys including numeric keys for inputting a desired number, wherein an application icon (2711, 2712, 2713) is displayed on an image of a key, if an application corresponding to the application icon (2711, 2712, 2713) is mapped to said key; - in response to an input on the image of the key to which the application is mapped, execute the application; and - in response to an input on an image of a numeric key to which no application is mapped, input a number corresponding to the numeric key; and wherein the controller is configured to, when a pointer of the remote control device is located on the image of the numeric key to which no application is mapped, display an application mapping indicator on said key to which the application is not mapped, and when the application mapping indicator is selected, to display a function key mapping window on the display unit and to receive a selection of an application from the function key mapping window, and to map the selected application to the numeric key, wherein the function key mapping window includes a list of applications; and wherein the controller is further configured to display an indicator with respect to an application mapped to another key in the function key mapping window, to indicate that the application is mapped to the another key. a display unit; a user input interface configured to receive a signal from a remote control device; and a controller configured to: - when a function key setup mode entry signal is received from the remote control device, display images of a plurality of keys of the remote control device on the display unit, the plurality of keys including numeric keys for inputting a desired number, wherein an application icon (2711, 2712, 2713) is displayed on an image of a key, if an application corresponding to the application icon (2711, 2712, 2713) is mapped to said key; - in response to an input on the image of the key to which the application is mapped, execute the application; and - in response to an input on an image of a numeric key to which no application is mapped, input a number corresponding to the numeric key; and - when a function key setup mode entry signal is received from the remote control device, display images of a plurality of keys of the remote control device on the display unit, the plurality of keys including numeric keys for inputting a desired number, wherein an application icon (2711, 2712, 2713) is displayed on an image of a key, if an application corresponding to the application icon (2711, 2712, 2713) is mapped to said key; - in response to an input on the image of the key to which the application is mapped, execute the application; and - in response to an input on an image of a numeric key to which no application is mapped, input a number corresponding to the numeric key; and wherein the controller is configured to, when a pointer of the remote control device is located on the image of the numeric key to which no application is mapped, display an application mapping indicator on said key to which the application is not mapped, and when the application mapping indicator is selected, to display a function key mapping window on the display unit and to receive a selection of an application from the function key mapping window, and to map the selected application to the numeric key, wherein the function key mapping window includes a list of applications; and wherein the controller is further configured to display an indicator with respect to an application mapped to another key in the function key mapping window, to indicate that the application is mapped to the another key.