The queue data structure has three main methods:
enqueue(adds a node to the back of the queue)
dequeue(removes node at the front of the queue)
peek(returns value of node at the front of the queue, without removing it)
A queue is a data structure composed of nodes, which follows a first in, first out (FIFO) protocol.
This is analogous to a line at a grocery store, for which the first customer in the queue is the first to checkout.