what is the meaning of this x = {0}; y = {1} to be the output 10 and 20

Question

int x = 10;
double y = 20;

Console.WriteLine("x = {0}; y = {1}", x, y);

Answer 1

It means it will insert 10 on {0} and 20 on {1} and print it that way. In this way you can build console outputs/strings dynamic.