Reverse Ajax refers to an Ajax design pattern that uses long-lived HTTP connections to enable low-latency communication between a web server and a browser. Basically it is a way of sending data from client to server and a mechanism for pushing server data back to the browser. This server–client communication takes one of two forms: * Client polling, the client repetitively queries (polls) the server and waits for an answer. * Server pushing, a connection between a server and client is kept open, the server sends data when available.