1. A terminal to provide a see-through input, the terminal comprising: a touchscreen to display a first application, to sense occurrence of a touch, and generate a touch signal in response to a sensed touch; and a control unit to determine whether the sensed touch is a general input for the first application or a see-through input for a second application according to the generated touch signal, the general input being different from the see-through input, wherein the first application is displayed on the touchscreen to at least partially overlap the second application, wherein a partial portion of the second application associated with a function of the second application and displayed on an area of the touchscreen receiving the sensed touch is processed in response to a determination that the sensed touch is the see-through input, wherein a partial portion of the first application associated with a function of the first application and displayed on the area of the touchscreen receiving the sensed touch is processed in response to a determination that the sensed touch is the general input, wherein the partial portion of the second application is overlapped with the partial portion of the first application in the area of the touchscreen receiving the sensed touch, wherein a transparency of the partial portion of the first application is changed based upon the sensed touch while a transparency of another partial portion of the first application is not changed, and wherein the see-through input is one of a pressure-based touch greater than a specific pressure, a long touch where the touch is maintained for longer than a specific period of time, and a combination touch including a specific key input of the terminal.