What is Alexa? How does it work?

Amazon’s new Alexa is a tool which I do not own. I have not felt compelled to purchase or even learn about this technology at this moment in time. My wife’s aunt and uncle have one and I became intrigued by the simple fact that they had decided to purchase an Alexa. Why? Who set it up for them?
This old dog has decided that it is time to explore in greater detail what an Alexa is and how it works. I will scour the web in various resources to teach you more about Alexa. My first post about Alexa is below and it references a great article from CNET: 15 Amazon Echo Alexa tips and tricks.

Amazon’s Alexa devices are loaded with features. Here we help you become more proficient with your Echo, Echo Dot or Tap.

Source: 15 Amazon Echo tips and tricks – CNET