Hello, I am new to C#, and I came across a tutorial about pointer:

int *x ;

Declares a pointer variable x, which can hold the address of an int type. The reference operator (&) can be used to get the memory address of a variable.

int x = 100;

The &x gives the memory address of the variable x, which we can assign to a pointer variable

I don't understand what that "address of" mean?