Give your gadgets a brain! Previously out of reach for the do-it-yourselfer, the tiny computers called microcontrollers are now so cheap and easy to use that anyone can make their stuff smart. It's called "physical computing" -- with a microcontroller, your gadget can sense the environment, talk to the internet or other gadgets, and make things happen in the real world by controlling motors, lights, or any electronic device. The Arduino is an easy-to-use microcontroller board -- it's like an R&D lab on your kitchen table for prototyping any gadget. We show you how to make one, and how to use Arduinos and other microcontrollers to make an automatic yogurt maker, a vintage Skype telephone, a gumball machine that recognizes your secret knock, and more. Plus, make a Helicopter Rocket, portable solar power pack, gourmet Sous Vide food cooker, treadmill desk, and more fun DIY projects.