In a nutshell, Google Chromecast Audio is a liberating piece of technology that gives you the freedom to create a wifi home audio system of whatever price and quality range that you choose.  And, believe it or not, with Google Chromecast Audio technology you can create a wifi home audio system that is superior to Sonos or Bose for a fraction of their cost.  My other post Looking for an Alternative to a Sonos Sound System? explains in more detail how to do this, however in this post I will stick to only explaining what Chromecast Audio is and how it works.  About the size of an Oreo cookie and for the price of just $35, Google Chromecast Audio is a wifi enabled device that can turn any active speaker into a wifi speaker–just like a Sonos speaker.  There are other ways to make traditional home audio speakers active, however for the purposes of this post I will be talking about speakers that are inherently active.  The definition of an active speaker is basically any speaker with an amplifier that is built in to the speaker.  In other words, unlike the traditional home audio speaker, an active speaker does not require an amplifier to power it.  So while an active doesn’t need an amplifier or speaker wire to make it work it does require a power source in the form of either an electrical outlet or battery.  The type of active speaker that most people are familiar with is a typical batter powered Bluetooth speaker.  Another type of active speaker that a lot of people aren’t familiar with is an active studio monitor.  There are many different brands and caliber of both types of speakers at price points to fit just about every budget, however the one feature that neither of these usually come with is wifi capability.  That being said, this is where Google Chromecast Audio comes in.  Think of a Chromecast Audio device as a small computer that  can connect to the internet just like a laptop computer can.  Similar to how your laptop computer can play audio from your favorite media platform (Slacker, Spotify, Google Play Music, and more), each Google Chromecast Audio device can do the same.  Also just as you would connect speakers to your laptop to listen to this music, you connect an active speaker to the Chromecast Audio device.  The only difference being that the Chromecast Audio device doesn’t have built-in speakers (or a screen) to play this music without being connected to an active speaker.  The Chromecast Audio device connects physically to your active speaker then you download to your smartphone and use the free Google Cast App to control your Chromecast Audio device and connect it to the internet (as well as to the music on your phone).  Think of your smartphone as the receiver in a traditional home audio system in that you use it to control what media your speakers play and which speakers play this music.  Once you have all of your Chromecast Audio devices configured in the Google Cast App on your smartphone all you have to do is open your favorite compatible media player on your smartphone.  The interface screen of your media player will now display the Google Cast Icon.  Press this icon and it will give you the choice of which Chromecast Audio device you would like to stream to.  Through the Google Cast App you can name each of your Chromecast Audio devices based which speaker it is connected to, which room it is in, or whatever you choose.  You can also create groups on the app according to which speakers you want to play depending on what you are doing or what room(s) you plan to be in.  For example, if you typically clean the kitchen and the living room at the same time and like to listen to music while doing so but don’t want to bother your spouse in the other room, you might want to create a group called kitchen + living room and include all devices in these two rooms for this group.  Then when you select the group kitchen + living room, all of (and only) the speakers in these two rooms will play.  You can have as many or as few Chromecast Audio devices as you would like and can also create as many groups as you want.  In addition, each Chromecast Audio device can each be parts of different groups.  For example, in addition to kitchen + living room, you may want to also have another group called living room + patio that you play when you have guests over.  I hope this all makes sense.  If you have any questions at all about Google Chromecast Audio, please fill in the contact form below or post in the comment section below and I will do my best to answer them.  Check out my post Build Your Own Wifi Sound System to learn how to create a wifi sound system that is superior to a Sonos for a fraction of the cost and check out my other post Looking for an Alternative to a Sonos Sound System? to learn how such a system compares to the popular Sonos system.