Microcontrollers are essentially low-powered computers on a chip. They have input/ output pins to which you can attach electronics so the microcontroller can, well, control things. Utilizing a microcontroller used to be quite a complex process, largely because the microcontroller needed to be programmed. This was often done in assembler or complex C. But there was a lot to learn before you could do anything useful. Because of this, it discouraged their use in casual projects where you just wanted to hack something together.
Enter the Arduino (Figure 6-1). The Arduino is a simple-to-use, low-cost, readymade board that lets you use a microcontroller in your projects with a minimum of fuss.
FIGURE 6-1 An Arduino Uno board