Welcome to our exploration of queues and deques in Ruby. These data structures are fundamental in programming, managing tasks in applications, from job scheduling to executing sequences of operations. In this lesson, our aim is to understand and implement queues and deques using Ruby's versatile array features. Let's dive in!

A queue operates on the "First In, First Out," or FIFO, principle, much like waiting your turn at a coffee shop. In Ruby, we can utilize arrays to implement queue functionality. The push method allows us to enqueue items, while shift can dequeue them.

The item "Apple" is removed first, illustrating the FIFO nature of queues.

Before removing items from a queue, we should verify that the queue is not empty. This check is crucial to avoid runtime errors during the dequeue process.

A deque, or "double-ended queue," permits adding and removing items from both ends. Ruby's arrays can manage deques via operations like push, (to add items to the left), (to remove from the right), and (to remove from the left).