Use your smartphone screen as a virtual 2×16 LCD
made for testing your ideas that uses an LCD before
interfacing your Arduino to a real one.
Learn more from the examples LCD Shield page.
This shield is one of the special shields. Special shields
allows your Arduino board to use some Arduino LCD Shield
capabilities your smartphone can do, like playing music, taking a picture,
getting notifications, accessing the clock data and
using the touch screen for various functions. Learn more from the
special shields tutorial.