Heap vs. Stack

• Once a function call runs to completion, any data on the stack created specifically for that function call will automatically be deleted. Any data on the heap will remain there until it’s manually deleted by the programmer.
• The stack is much faster than the heap. This is because of the way that memory is allocated on the stack. Allocating memory on the stack is as simple as moving the stack pointer up.
• Data on the stack is automatically deallocated when variables go out of scope. However, in languages like C and C++, data stored on the heap has to be deleted manually by the programmer using one of the built in keywords like free, delete, or delete[ ].

stack: static memory
heap: dynamic memory