JavaScript was originally created as a client-side scripting language for web browsers, enabling developers to create interactive web pages. However, with the advent of Node.js, JavaScript expanded its reach to the server-side, opening up new possibilities for application development. Node.js is a runtime environment based on the V8 JavaScript engine, which is used by Google Chrome, allowing JavaScript to be executed outside of the browser.

Basic Characteristics of Node.js

1. Asynchronous and Event-driven Architecture: Node.js utilizes non-blocking I/O operations, meaning all input and output operations occur asynchronously. This allows Node.js to efficiently handle thousands of parallel connections with minimal overhead.

2. Single-threaded Model with Event Loop: Despite running in a single thread, Node.js' event loop enables it to handle multiple requests concurrently using callbacks, promises, and async/await, enhancing performance and scalability of applications.

3. NPM (Node Package Manager): Node.js comes with a built-in package manager, npm, which is the world's largest software library. It facilitates easy sharing and utilization of third-party code.

Usage of Node.js

Node.js can be used for various types of applications, ranging from web servers and APIs to automation tools and real-time data processing systems. Some of the common use cases include:

• Web Application Development: Node.js enables the creation of fast and scalable web servers and applications due to its non-blocking architecture.
• API Servers: With Node.js, you can easily develop RESTful APIs that serve as the backend for web and mobile applications.
• Real-time Applications: Thanks to its efficient handling of I/O operations, Node.js is ideal for developing real-time applications such as chats or games.

Basic Steps to Get Started with Node.js

1. Install Node.js: Visit the official Node.js website (nodejs.org) where you can download and install the latest version for your operating system.

2. Create Your First Application: After installation, you can create your first simple server. Create a file, for example, server.js, and use the following code:

   const http = require('http');
   
   const server = http.createServer((req, res) => {
     res.statusCode = 200;
     res.setHeader('Content-Type', 'text/plain');
     res.end('Hello World\n');
   });
   
   server.listen(3000, () => {
     console.log('Server running at http://localhost:3000/');
   });
   

3. Run the Server: Open a terminal, navigate to the folder containing your application, and run the command node server.js. Your server should now be running and responding to requests on port 3000.

Node.js represents a revolutionary step in JavaScript development by extending its usage beyond the browser and enabling the development of fast, scalable, and efficient server-side applications. Its asynchronous approach, event-driven support, and extensive package ecosystem make Node.js a powerful tool for modern developers.