This book is for programmers who want to create web applications that can commu‐ nicate bidirectionally between server and client and who are looking to avoid using hacks that are prevalent on the Web today. The promise of WebSocket is a better way, based on standards and supported by all modern browsers, with sensible fallback options for those who need to support it. For those who haven’t considered Web‐ Socket, put down the Comet tutorial you have been reading.