This may be a little bit stale, but for people sumbling upon this thread, I have added a few sentences to clarify the proper understanding of the destictions called Stacks and Queues.

Please remember that a Stack data structure as mentioned by others is a list where nodes (or items) are added in a last in first out fashion LIFO. This is conceptually similar to an actual stack of coins where the rules only allow you to add coins (Push)...