AirPlay 2?
Sonos launched its multiroom audio solution in 2002, utilising a circle controller suspiciously similar to that of Apple’s crazy-popular iPod. Rather than releasing its team of legal attack dogs, Apple responded in kind with the absolutely Sonos-esque AirTunes, released alongside iOS 4 in 2004. This enabled the sending of audio from iTunes to a speaker-connected AirPort Express, though AirTunes was, given the benefit of hindsight, a fairly limited protocol; it wasn’t until 2010, when Apple upped its abilities to go beyond audio streaming, that the rebranded AirPlay came into its own.
It’s a very easy system to understand:
