Arduino is an open-source physical computing platform designed to make experimenting with electronics more fun and intuitive.  Arduino has its own unique, simplified programming language, a vast support network, and thousands of potential uses, making it the perfect platform for both beginner and advanced DIY enthusiasts.

This is a video of how aurduino works 

this is how i chnage the code and how the cirtcuit works  

this how cirucit 9 works with the sketch changed, with this combination the aurdiono is playinh the song "Happy birthday"