Along with HTML5, WHATWG Web Applications 1.0 introduces events which
flow from web server to the web browsers and they are called
Server-Sent Events (SSE). Using SSE you can push DOM (Document Object Model) events continuously
from your web server to the visitor's browser.
The event streaming approach opens a persistent connection to the
server, sending data to the client when new information is available,
eliminating the need for continuous polling.
Server-sent events standardizes how we stream data from the server to the client.