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# Node.js Tutorial  Simply put, Node.js is JavaScript running on the server side. Node.js is a platform built on top of the Chrome JavaScript runtime. Node.js is an event-driven, I/O server-side JavaScript environment, based on Google's V8 engine. The V8 engine executes Javascript very fast, with excellent performance. * * * ## Who is this tutorial for? If you are a front-end programmer who doesn't know dynamic programming languages like PHP, Python, or Ruby, and you want to create your own server, then Node.js is an excellent choice. Node.js is JavaScript running on the server side. If you are familiar with Javascript, you will find it very easy to learn Node.js. Of course, if you are a back-end programmer looking to deploy some high-performance services, learning Node.js is also a very good choice. * * * ## Prerequisites Before continuing with this tutorial, you should understand some basic computer programming terminology. If you have learned programming languages like Javascript, PHP, Java, etc., it will help you understand Node.js programming more quickly. * * * ## Node.js Features * **Single-threaded and Event-driven Architecture**: Node.js uses a single thread to handle requests, but through its event-driven and non-blocking I/O operation characteristics, it can efficiently handle a large number of concurrent connections without blocking threads. * **Asynchronous and Non-blocking I/O**: This allows Node.js to handle high-concurrency requests, making it very suitable for I/O-intensive applications such as file reading, database operations, and network requests. * **Cross-platform Support**: Node.js can run on multiple operating systems like Windows, Linux, and macOS. * **Vast Ecosystem**: Node.js has an ecosystem called npm (Node Package Manager), which contains a rich collection of third-party libraries and modules that can be used to extend functionality and accelerate development. * * * ## Use Cases for Node.js * **Web Servers**: Due to its efficient handling of concurrent requests, Node.js is often used to build fast, scalable web servers. * **Real-time Applications**: Such as chat applications, real-time collaboration tools, etc. * **API Services**: Node.js is well-suited for developing RESTful APIs and GraphQL services. * **Command-line Tools**: Node.js can also be used to build CLI tools, leveraging its easy-to-use libraries and package manager for rapid development. * * * ## Version Used We can use the following command to check the current Node version: $ node -v v4.4.3 **Note:** There may be differences between versions. * * * ## First Node.js Program: Hello World! ### Script Mode Here is our first Node.js program: ## Example console.log("Hello World"); [Run Example »](#) Save this file with the name helloworld.js, and execute it using the node command: node helloworld.js After the program executes successfully, it will output Hello World in the terminal. ### Interactive Mode Open the terminal, type node to enter the command interactive mode. You can enter a code statement and execute it immediately to see the result, for example: $ node > console.log('Hello World!');Hello World! * * * ## Gif Example Demonstration Next, we will demonstrate the example operation through a Gif image: !(#)