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

From the creator of Node.js, Deno is a secure runtime for JavaScript and TypeScript that addresses Node’s shortcomings ...

Node.js offers simplicity without sacrificing performance. It allows developers to use JavaScript for both frontend and backend, which reduces complexity and speeds up development cycles.

Because it's simple and scalable, organizations are using Node.js to not only build applications, but to do cloud-based application development and build IaaS and SaaS solutions.