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.
The pros for the auto function is that you don't have to set the brightness it does it automatically. The cons for it is there is only a set brightness you have and you don't have the freedom to change it