<ul>
<li>What are the stack and heap?</li>
<li>Where are they located physically in a computer's memory?</li>
<li>To what extent are they controlled by the OS or language run-time?</li>
<li>What is their scope?</li>
<li>What determines their sizes?</li>
<li>What makes one faster?</li>
</ul>

Stack:
Stored in computer RAM just like the heap.
Variables created on the stack will go out of scope and are automatically deallocated.
Much faster to allocate in comparison to variables on the heap.
Implemented with an actual stack data structure.
Stores local data, return addresses, used for parameter passing.
Can have a stack overflow when too much of the stack is used (mostly from infinite or too deep recursion, very large allocations).
Data created on the stack can be used without pointers.
You would use the stack if you know exactly how much data you need to allocate before compile time and it is not too big.
Usually has a maximum size already determined when your program starts.
Heap:
Stored in computer RAM just like the stack.
In C++, variables on the heap must be destroyed manually and never fall out of scope. The data is freed with
```
delete
```
,
```
delete[]
```
, or
```
free
```
.
Slower to allocate in comparison to variables on the stack.
Used on demand to allocate a block of data for use by the program.
Can have fragmentation when there are a lot of allocations and deallocations.
In C++ or C, data created on the heap will be pointed to by pointers and allocated with
```
new
```
or
```
malloc
```
respectively.
Can have allocation failures if too big of a buffer is requested to be allocated.
You would use the heap if you don't know exactly how much data you will need at run time or if you need to allocate a lot of data.
Responsible for memory leaks.
Example:
```
```
int foo()
{
  char *pBuffer; //<--nothing allocated yet (excluding the pointer itself, which is allocated here on the stack).
  bool b = true; // Allocated on the stack.
  if(b)
  {
    //Create 500 bytes on the stack
    char buffer[500];

    //Create 500 bytes on the heap
    pBuffer = new char[500];

   }//<-- buffer is deallocated here, pBuffer is not
}//<--- oops there's a memory leak, I should have called delete[] pBuffer;
```
```