How do I find this node?

In this video when this guy add a ‘Fresnel Node’ and click something then a small green node call ‘Viewer’ has appeared (From 2:56). I tried to add that 'viewer but I can’t and don’t know to how. How DO I add the 'viewer node?

I think you have to enable Node Wrangler addon and then shift - ctrl - click the node you want to see

AH! Shift+Ctrl Thank U ^^