 This time around we're going to be covering queues, which for historical reasons have a very weird spelling. Queue is also one of the simpler data types. I wrestled a little bit with whether to cover a stack or a queue first, and I felt a stack first just because there are special types of queues, but not really special types of stacks. Similarly to the stack, the queue really just has two fundamental operations. The first is enqueue, and if we enqueue a one, you get a one on there. Where it gets a little bit different is if you enqueue a two, the two is behind the one, the front is still one. Enqueue a three, you have a three behind the two, and enqueue a four, you have a four behind the three. The other operation being dequeue. In this instance, the one is dequeued because it was at the front. Now the front is two, so dequeuing the front again will yield you a two, and dequeuing again will yield you a three, and dequeuing again will yield you a four. The queue is now empty. As for some uses of the queue, this one should be a little bit more obvious to most of you. You've seen these waiting in line for the cashier or food or whatever. It's very common in task ordering and task management. That's probably the single biggest thing that I've seen it used for. It also has uses with expiring inventory. Hopefully this is something that you do, but not everyone does as some past experience as a cook has shown me. To keep product ordered appropriately, when you get new stuff, it should be placed after the existing stuff, so that you follow the FIFO or first in, first out principle that a queue helps enforce. And it's also used in FIFO accounting, which is the more common type of accounting that most people just sort of think of. Next up, we'll be doing lists.