Node.js is a JavaScript runtime environment that allows you to execute JavaScript code outside of a browser. It is mainly used to create backend applications and services, such as web servers, APIs, and database systems.
For example, Node.js can be used to create a web server that can serve web pages to users. It can also be used to create an API that can be used to access a database. Additionally, Node.js can be used to create a database system that can store and retrieve data from a database.