Node JS is designed to build scalable network applications. Its an open source, cross-platform, backend technology based on JavaScript runtime environment that runs on the V8 engine and executes a JavaScript outside a web browser. Node JS can be used for both backend and the frontend.
Node JS is preferred when fast and scalable web development is required. Its simpler than JAVA and ideal for full stack developers. It offers faster and easier writing of code. It lets you store many libraries in one line because it has a node package manager.
Node JS has recently become very popular amongst startups as their most preferred back-end technology. If speed is an important aspect of your application, then Node JS is a better choice compared to other frameworks like PHP.