An Arduino shield is a modular circuit board that plugs directly into the pin headers of the Arduino board. These shields will add extra functionality to the Arduino board. If we are looking to connect to the internet, do speech recognition, control DC motors or add other functionality to the Arduino, there is probably a shield that can help us. While we are not required to use shields, they do make adding extra functionality to our Arduino boards very easy.
The following photograph shows examples of a few shields. We will be using shields in some of our sample projects later in this book:
A shield fits on top of the Arduino ...
