[eternalban]

Generally, the "heap" is the addressable memory assigned to the process. E.g. you malloc a byte array and gain a reference to the (byte[] rep.) memory object in heap. The life-cycle of a memory object in heap is explicitly controlled by OS (and sometimes the language e.g. C/Obj-C/etc via freeing the heap memory object). Languages with garbage collectors do this implicitly.

The "stack" is the dynamic structure -- its a stack :) -- that maintains the nested call/method/function frames from the initial entry point (e.g. main(..) in C family) so it maintains the path traversing the invocation/call graph to the current executing call/method/function. The 'objects' in a stack are call/function/method parameters, various metadata (e.g. obj ptr in some oo langauges). The life cycle of objects in stack is scoped by the call/function/method itself. Further, typically attempts are made to store (current) stack objects in CPU registers so as to avoid incurring memory access latencies.