A display device, comprising: a body; a roller rotatably installed in the body; a flexible display configured to be wound or unwound from the roller in response to a rotation of the roller; and a controller configured to: - change a screen size for displaying information related to a prescribed content according to the winding or the unwinding of the flexible display; and - execute a multitude of modes (M1, M2, M3, M4) for displaying different quantities of information according to the changed screen sizes, respectively, - activate the display device according to a first mode included in the multitude of the modes for displaying first information including a brief information on the content on the flexible display; - expand the flexible display in a first size appropriate for displaying the first information from the body, - wherein the first information comprises a reminder or notification for the content to be broadcasted or played and a summary of the content for providing a user with a prescribed information; and - automatically perform the first mode under a prescribed condition, wherein the condition comprises at least one of when a preset time arrives, when a user is preset at home or approaches the display device, and when the user turns on a power of the display device, and wherein the controller is configured to turn off a portion of the display hidden in the body. a body; a roller rotatably installed in the body; a flexible display configured to be wound or unwound from the roller in response to a rotation of the roller; and a controller configured to: - change a screen size for displaying information related to a prescribed content according to the winding or the unwinding of the flexible display; and - execute a multitude of modes (M1, M2, M3, M4) for displaying different quantities of information according to the changed screen sizes, respectively, - activate the display device according to a first mode included in the multitude of the modes for displaying first information including a brief information on the content on the flexible display; - expand the flexible display in a first size appropriate for displaying the first information from the body, - wherein the first information comprises a reminder or notification for the content to be broadcasted or played and a summary of the content for providing a user with a prescribed information; and - automatically perform the first mode under a prescribed condition, - change a screen size for displaying information related to a prescribed content according to the winding or the unwinding of the flexible display; and - execute a multitude of modes (M1, M2, M3, M4) for displaying different quantities of information according to the changed screen sizes, respectively, - activate the display device according to a first mode included in the multitude of the modes for displaying first information including a brief information on the content on the flexible display; - expand the flexible display in a first size appropriate for displaying the first information from the body, - wherein the first information comprises a reminder or notification for the content to be broadcasted or played and a summary of the content for providing a user with a prescribed information; and - automatically perform the first mode under a prescribed condition, wherein the condition comprises at least one of when a preset time arrives, when a user is preset at home or approaches the display device, and when the user turns on a power of the display device, and wherein the controller is configured to turn off a portion of the display hidden in the body.