While the concept of running JavaScript on a server isn't new, its popularity, stability, and features are greatly expanded with Node.js. Early on, server-side JavaScript was abandoned but came to light again in 2009 with the creation of Node.js.
Node.js reduces the context-switching mental overhead for developers by working with the same fundamental grammar on both the client and server side. The same developer can work through the whole stack rather seamlessly because there are considerable similarities between the client-side work and how to operate with Node.js on the server. Along with a difference in approach also comes a different fundamental paradigm for handling requests to the server, compared to other more traditional implementations.
JavaScript: it's not just client-side anymore!
In the next chapter, we're going to take a deep dive into the grammar of JavaScript: syntax, semantics, and best practices.