Two years ago we launched Google Cast, an extension for Chrome that allowed you to show content from your favorite websites on the best screen in your home—your TV—using Chromecast.. The Chromecast Extension installs in Google Chrome and allows you to cast your Chrome browser tabs to your Chromecast.
Chromecast built-in is a technology that lets you cast your favorite entertainment and apps from your phone, tablet or laptop right to your TV or speakers.

Google Chromecast Extension need to install in Google Chrome browser that allows you to cast / mirror your Chrome browser tabs and extend desktop to your HD TV with Chromecast device.

This makes it easy for you to cast videos from Amazon Instant Video, Vimeo, Ted and more right to your television.

Teachers: Download this extension to set up your device for wireless screen sharing. Just install the extension, give your device a name, and invite your students to cast. Whether watching your favorite show on Netflix, or sharing a photo slideshow at a family gathering, Google Cast makes it easy to extend the web to the big screen.
Download and install google chrome browser by visit chrome official site and follow instruction (Google Chrome may automatically launch): Cast for Education allows you to turn your computer into a wireless projector for screen sharing from another device. The Chromecast Extension is also very helpful if you are trying to display a website to a group of people.