In early 1990s, HTTP was designed to allow data communication over the web. It's page-centric and the only ways for users to interact were to refresh the page or follow a link. And most of our web consisted of static pages until AJAX became a standard.
AJAX
WebSockets
A Gap in the Web Platform
WebRTC
Opportunities
Remote office
Co-working service
Video conferencing
Tele-education
Healthcare/Tele-medicine
Customer Service
Telemetry
etc.
Javascript API
Obtain user media: getUserMedia
Communicate with other browsers: RTCPeerConnection