What is the stack pointer inside the CPU?

The stack pointer is a special-purpose register in the CPU that holds the address of the top of the current stack in memory. The stack is a data structure used for managing function calls, local variables, and control flow, operating in a last-in, first-out (LIFO) manner. As functions are called and return, the stack pointer is updated to reflect the current position of the stack, ensuring proper access to function parameters and local data. This mechanism is crucial for maintaining the execution context during program runtime.