What is Node.js, and what are its main features?

Sample Answer: Node.js is an open-source, server-side JavaScript runtime built on Chrome’s V8 JavaScript engine. It allows developers to build scalable, high-performance network applications using JavaScript, a language traditionally associated with client-side scripting in web browsers.

Main Features of Node.js:

1. Non-blocking I/O Model: Node.js is built on an event-driven, non-blocking I/O model, which allows it to handle concurrent connections efficiently. Instead of waiting for I/O operations to complete before moving to the next task, Node.js uses asynchronous callbacks to continue processing other tasks while waiting for I/O operations to complete.
2. Single-threaded, Event-Driven Architecture: Node.js uses a single-threaded event loop to handle multiple concurrent connections. This architecture allows Node.js to handle thousands of simultaneous connections with minimal overhead, making it well-suited for building real-time applications such as chat servers, gaming servers, and streaming platforms.
3. CommonJS Modules: Node.js uses the CommonJS module system, which allows developers to break their code into reusable modules. Modules encapsulate related functionality and provide a clean way to organize code, manage dependencies, and promote code reusability.
4. NPM (Node Package Manager): Node.js comes with npm, a powerful package manager that hosts over a million packages of reusable code. Developers can easily install, manage, and publish packages using npm, making it easy to integrate third-party libraries and frameworks into Node.js applications.
5. Built-in APIs: Node.js provides a rich set of built-in APIs for performing various tasks such as file I/O operations, networking, cryptography, and more. These APIs, along with the vast ecosystem of npm packages, enable developers to build a wide range of applications, from simple web servers to complex microservices architectures.
6. Cross-platform: Node.js is cross-platform, meaning it runs on various operating systems such as Windows, macOS, and Linux. This allows developers to write code once and deploy it across different environments without making significant changes, increasing development efficiency and reducing time to market.

In summary, Node.js is a lightweight, efficient, and scalable platform for building server-side applications using JavaScript. Its non-blocking I/O model, event-driven architecture, module system, package manager, built-in APIs, and cross-platform support make it a popular choice for building modern web applications, APIs, and microservices.