A display device and a method are provided. The display device includes a network interface connected to a network; an internal storage configured to store at least one content; a display; and a processor configured to control the display to display, in a first area of a user interface (UI) screen, a category list, including a video category and a photo category, to enable selection of one category from the list, and control the display to display, in a second area of the UI screen, at least one thumbnail image corresponding to at least one content stored in at least one external device connected through the network interface and at least one thumbnail image corresponding to the at least one content stored in the internal storage.