Let's summarize what we have learned in this chapter. We connected three LEDs to a Raspberry Pi board. After that, we made these LEDs blink. Then, we read the Raspberry Pi GPIO input. Finally, we learned to display several colors through an RGB LED.

In the next chapter, we will work with 7-segment display and a shift register to manipulate several 7-segment display modules. We will also build a countdown timer app by utilizing a 7-segment module.