You have learned how to control a single servo and an entire set with a servo control shield. Now you can not only build robots that role, but you can also build robots that walk. You know how to easily add even more servos to act as arms, or any number of other functions. However, your robot really can't sense the outside world yet, and is reliant entirely upon someone to control it.

In the next chapter, you'll add sensors so that your robot can avoid/find obstacles and other objects.