Distinguish between the frame pointer and the stack pointer.

What will be an ideal response?

The stack pointer points to the top of the stack and as more or less stack space is needed will change position during the execution of a particular piece of code (e.g. function) . Since it is common to reference the location of variables stored on the stack as an offset from the stack pointer this movement becomes problematic. A solution is to use another register to store the location of a fixed reference point that will be constant throughout the execution of some particular piece of code (e.g. function). Note: This is not to say that when a function calls another function the frame pointer will remain fixed. It will not. Rather it will be changed on call and reestablished upon return thus for all execution of an given functions own code it will be fixed.