1. A digital television receiver for processing a search operation, the digital television receiver comprising: a user interface configured to receive a first control signal for executing a first application in a normal mode and a second control signal for requesting a search mode from a remote controller; a storage configured to store application data of the first application; a controller configured to: detect, while displaying the first application in the normal mode, said second control signal, control automatically entering into the search mode in response to the detected second control signal, display, in the search mode, a second application including a search window and a menu item including a first icon along with the first application on a single display screen, wherein the first icon corresponds to a third application for the search operation; and perform, in the search mode, the search operation; and a display, wherein the first application is at least one of a broadcast program, a web application, a video, an image, a streaming content or a downloaded content, wherein the second application is switched into the third application in response to selecting the first icon, wherein the search window displays a plurality of search terms, a second icon at each search term for selecting the corresponding search term, and a search button, wherein, when the second icons are selected, the search window displays a new recommended search term based on at least two search terms corresponding to the selected second icons from the plurality of search terms, and wherein at least one of the first control signal and the second control signal is received through at least one of a physical or soft button, a touch, a gesture and a voice of the distal television receiver or the remote controller.