Remember the following points before moving to the next chapter.

• Do not power motors directly from the Arduino board
• Arduino's GND pin is used to achieve a common ground between multiple power sources
• The transistor is continuously switched ON and OFF by using the analogWrite() function to send PWM signals via a PWM capable digital pin
• The analogWrite() function can be used with Arduino's digital pins
• Interrupts are used to handle user inputs in a responsive manner