The document discusses socket applications and real-time communication. It describes common examples like chat, live feeds, and games. It then explains the typical solution of using AJAX requests and the problems with that approach. The proposed solution is to use a multi-threaded model with asynchronous I/O and the reactor pattern to process requests while waiting for network responses. Various tools for implementing this pattern in Ruby and JavaScript are also mentioned, including Pusher, Socket.IO, and SocketStream.