(All My Notes are attributed/sourced from the Resources directly preceding them.)
Summary
Stacks follow a LIFO principle for memory management. This means that the last item added into the stack is the first item that is retrieved/removed.
Queues follow a FIFO principle for memory management. This means that the first item added into the queue is the first item that is retrieved/removed.
Peeking in either stack or queue only allows you to see what is at the top of the list. For stack this is the last item in the list and for queues the first item in the list.