In Chapter 4, Accessing the GPIO Pins, you learned how to connect with the outside world using jumper wires, breadboards, and components. In this chapter, you'll learn different connection approaches to show how you can connect an additional capability to Arduino using hardware shields designed for Arduino. Specifically, I'll cover two topics: how to add a functionalities by adding hardware that is designed to plug into Arduino or shields and how to connect several types of displays to Arduino. We'll use several different types of display shields to illustrate the different communication modes that can be used to address the different types of hardware.