A web application basically has three parts:

• website (frontend)
• server (backend)
• database (backend)

The website (frontend) is the part of the web application with which the user interacts.

The server (backend) can use NodeJS, Java, Python, etc.

The database (backend) uses relational or non-relational databases.

A client makes requests from the client side of the application. The server manages the requests from the client. The server does processing and calculations for the validation of the client request. After the validation, a response is sent to the client. The NodeJS framework of JavaScript is used for the processing and calculations.

Node.js is used for the server side of a web application. Node.js is a JavaScript runtime environment and library for running web applications. It is open-source and cross-platform, built on Chrome’s V8 JavaScript engine. Node.js is the most popular solution to run JavaScript outside of a web browser. It was developed in 2009 by Ryan Dahla. More information about Node.js is available at nodejs.org.

npm is the Node.js package manager. The npm registry is also the world’s largest software registry. It is a large public database of JavaScript packages (online repository for JavaScript code) and the meta-information (metadata) surrounding it. There is a public npm registry and there are private npm registries. The public npm registry has over 50,000 packages available. Open source developers from around the world use npm to share and borrow packages, and many organizations use npm to manage private software development. A package is a file or directory that is described by a package.json file. More information about npm is available at What is npm?

To download packages from the public npm registry or a private npm registry (and to publish packages to registries), you must install Node.js and the npm command line interface. 

JSON stands for JavaScript Object Notation. It was developed by Douglas Crawford and Chip Morningstar. Many people pronounce it “Jay-sahn.”