Physical Computing is all around us. Our smartphones, our cars, our washing machines, all are examplesof physical computing. Even our toaster has become smart these days. Smart meaning controlled by amicro-controller, and physical computing meaning some electronic components controlled by a micro-controller. If these electronic components are electric motors, magnets or other actuators, then theelectronic becomes physical, meaning something moves. But physical also means measuring things liketemperature, sound, and light. We want to learn about all these, about electronics, about electroniccomponents, and about micro-controllers.We start with a little bit of history, not because usually that's what one does, but because many of theconcepts and components become really easy to grasp and understand. After having seen some of theorigins, we then learn about simple electric circuits and simple electronic components. We get to knowbatteries, switches, resistors, capacitors and inductors. And we will briefly hear about Ohms law andKirchhoff's circuit laws. We also get to learn how to use the circuit simulator. Then the active electroniccomponents follow, such as diodes, LEDs, and transistors. We learn about the different type of diodesthat there are and what they are used for. We get to know transistors, bipolar and field-effect, and how touse them as switches and as amplifiers. We get to see the multivibrators, especially the astable and thebistable, and learn why they are so important for computers. After these introductory chapters, we haveenough of a foundation to do some real physical computing. We will use an Arduino and connect it withthe different electronic components we learned about in the previous chapters.