Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
Node.js’ package ecosystem, npm, is the largest ecosystem of open source libraries in the world.
I/O refers to input/output. It can be anything ranging from reading/writing local files to making an HTTP request to an API.
I/O takes time and hence blocks other functions.
Consider a scenario where we request a backend database for the details of user1 and user2 and then print them on the screen/console. The response to this request takes time, but both of the user data requests can be carried out independently and at the same time.