Node.js is a powerful, open-source JavaScript runtime environment that allows developers to execute JavaScript code outside of a web browser. Traditionally, JavaScript was used only for client-side scripting in browsers, but Node.js enables it to run on servers, making it possible to build fast, scalable network applications.

It is built on Chrome's V8 JavaScript engine and uses an event-driven, non-blocking I/O model. This means it can handle many connections simultaneously without getting bogged down, which is ideal for:

• Real-time applications like chat or gaming platforms
• APIs (Application Programming Interfaces) and backend services
• Data streaming applications
• Server-side web applications

A key feature is npm (Node Package Manager), the world's largest ecosystem of open-source libraries. With npm, you can easily add pre-built modules to your project, saving significant development time.

In summary, Node.js lets you use JavaScript for both the front-end and back-end of web applications, creating a more unified and efficient development process. It's a popular choice for modern web hosting because it efficiently manages resources and supports the fast-paced demands of today's web.