Best answer by Ryan S
The Sonos players (speakers) are all smart speakers. Each one of them has a computer built into it, much more than just a wireless speaker. They each play to themselves, you just tell it what to do with a controller. You can also group rooms(any player(s)) together in any combination and they'll play the same thing, in sync.
You can start with a single Sonos player, like a PLAY:5. It'll connect to your wireless network, and you can use your various mobile devices and computers to tell it what to do. From there you can build up to multiple rooms and play around with the options.
The real "work" when it comes to streaming is being handled by your Sonos players. This also means if you get a phone call, music keeps playing. If you walk out of the house and take every single one of your Sonos controllers with you, music keeps on playing. But if you want to stop the music, you can just grab the nearest controller and say stop.