My question is:

When I press the "Shut down" button in Windows/Linux,the computer shutdowns.How did the command "Shut down" actually make the computer Physically shutdown?

To make my point clear:

When we kick a ball,there is physical contact between the ball and our leg,for the ball to move.So how is the physical connection achieved between softwares and hardwares?How does plain text of codes make the computer do what it does?

(Noob question,I know but it has been irritating me for quite sometime now) -Aby