Node.js has revolutionized the way developers build server-side applications. Among its myriad features, the following standout as essential for every developer:

1. Asynchronous Programming: Node.js operates on a non-blocking I/O model, allowing multiple operations to happen simultaneously, which significantly improves performance.
2. NPM: The Node Package Manager (NPM) is the world's largest ecosystem of open-source libraries, facilitating easy package management and dependency handling.
3. Event-Driven Architecture: Node.js employs an event-driven architecture, enabling it to handle multiple connections concurrently, making it ideal for real-time applications.
4. Cross-Platform: With Node.js, developers can build applications that run smoothly across various operating systems.
5. Single Programming Language: Developers can use JavaScript on both the client and server sides, simplifying the development process.

In addition to the aforementioned features, several others are equally impactful:

6. Microservices Support: Node.js encourages a microservices architecture, allowing developers to create scalable and maintainable applications.
7. Built-in Debugging: Advanced debugging tools are integrated into Node.js, making it easier for developers to troubleshoot issues during development.
8. Robust Community: The Node.js community is vast and active, providing continuous support and updates to the framework.
9. Streamlined Development: With tools like Express.js, developers can build web applications quickly and efficiently.
10. Real-Time Data: Node.js is highly efficient for applications requiring real-time data, such as chats and gaming applications.

Building scalable applications with Node.js requires a solid understanding of its non-blocking architecture and asynchronous features. To start, you should consider employing a modular structure in your application. This means separating your code into distinct modules that can handle different pieces of functionality. Utilizing frameworks like Express.js can simplify the routing process and improve code maintainability. Additionally, you should take advantage of Node's event-driven nature, allowing your application to handle multiple connections concurrently without getting bogged down.

Another critical aspect of developing scalable Node.js applications is the effective use of databases. Opting for a NoSQL database like MongoDB can enhance scalability due to its flexible schema and ability to handle large volumes of data without sacrificing performance. Moreover, implementing caching strategies using tools like Redis can significantly reduce database load and improve response times. Lastly, consider employing cloud services such as AWS or Azure to facilitate horizontal scaling, ensuring your application can grow seamlessly as user demand increases.

Node.js is an open-source, cross-platform runtime environment that allows developers to execute JavaScript code on the server side. This technology, built on the V8 JavaScript engine developed by Google, enables the creation of highly efficient and scalable network applications. Unlike traditional web development methods where JavaScript is confined to the browser, Node.js allows it to interact with the server, facilitating full-stack JavaScript development. Thanks to its non-blocking, event-driven architecture, Node.js is particularly well-suited for handling multiple connections simultaneously, making it a popular choice for real-time applications such as chat applications and online gaming.

In the context of modern web development, the importance of Node.js cannot be overstated. It supports the JavaScript ecosystem extensively, providing a unified language for both front-end and back-end development. This significantly reduces the complexity of development workflows, as developers can write both client-side and server-side code in one language. Additionally, with its vast package ecosystem, known as npm (Node Package Manager), developers have access to thousands of libraries and frameworks that can accelerate the development process. As a result, Node.js has become an essential tool for building lightweight, high-performance, and responsive web applications that can meet the demands of today’s fast-paced digital landscape.