First in, first out (FIFO) is a method for organising a data buffer so that the first entry is processed first.
It is modelled on a first-come, first-served queue.
This means that once a new element is added, all elements that were previously added must be removed before the new element can be removed.
A last in, first out (LIFO) approach is the opposite. This means that the most recent request is handled next, while the oldest request is only handled when it is the last remaining request on the queue.
