Always test your pages using Google’s own tools and third-party resources to view the rendered HTML to make sure all your content is showing up.

Node.js is a lean, fast, cross-platform JavaScript runtime environment that is useful for both servers and desktop applications.

The HTML is parsed, JavaScript is executed, and the result is the DOM. The content of a web page is not (just) source code, it’s the DOM. This makes it pretty important.

The JavaScript is still working behind the scenes. Essentially, we get a more granular HTML syntax, which can just load segments instead of whole pages, and can submit Ajax requests.