As you’ll see in the next few chapters, you can use the GPIO pins on the Raspberry Pi to connect to sensors or things like blinking LEDs and motors. If you have experience using the Arduino microcontroller development platform, you can also use that alongside with the Raspberry Pi.
When the Raspberry Pi was first announced, a lot of people asked if this was an Arduino-killer. For about the same price you can get much more processing power; why use Arduino when you have a Pi? It turns out the two platforms are actually complementary, and the Raspberry Pi makes a great host for the Arduino. There are a few other cases where you might want to Arduino and the Pi together: