So far we have simply looked at pointers to standard variables. However, C++ also allows the use of pointers that point to other pointers. A pointer to a pointer is often referred to as multiple indirection. Because a pointer is simply an indirect method of accessing a variable, then a pointer to a pointer would be multiple indirection. To create a pointer to a pointer, we only need to add an asterisk (*) for each level of reference.
char x; char * y; char ** z; x = 'a'; y = &x; z = &y;
The truth is that you can program for years and never have a particularly compelling need to implement pointers to pointers. In addition, pointers to pointers will not be used in this book.