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The Stack and the Heap

Both the Stack and the Heap are parts of the memory that is accessible to an app during runtime.

Stack

The Stack stores values in a last in, first out fashion.
All values stored must have a known fixed size.
- Data with unknown or changeable size must be stored on the Heap instead.
Are stored on the Stack:
- Arguments and local variables when calling a function.

Heap

The Heap is less organized than the Stack
When allocating on the Heap, the memory allocator:
1. Looks for an empty spot for the requested size.
2. Marks the spot as reserved.
3. Returns a pointer to the spot.
- The pointer is then usually stored on the Stack. When we want to access the data, we must follow the pointer to the Heap.

Stack vs Heap

Pushing to the Stack is faster than allocating on the Heap because the Stack doesn't need to find an empty spot.
Accessing data from the Stack is also faster because we don't have to jump around in the memory and to follow pointers.

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