hi all.
i have a very simple question. what does a black circle mean on the right of C chord diagram. you can see it on any song found here that has the C chord when you point the cursor over the letter C for example? its a small black circle over the A string? What do the white circles mean?

Thanks a lot in advance from serbia.
i am very greatfull for your answer or explanation
ok thanx for the reply i found out. it marks the string where the root note is. ring a bell now-