The event loop in Node.js is a continuous loop that is responsible for executing asynchronous callbacks when an event occurs. It is the mechanism that allows Node.js to perform non-blocking I/O operations — despite the single-threaded nature of JavaScript.
Example:
Let’s say you have a Node.js application that needs to read a file from the disk. Normally, this would be a blocking operation, meaning that the application would freeze until the file is read. However, with the event loop, the application can register a callback function that will be executed when the file has been read. This way, the application can continue to do other tasks while the file is being read, and when the file is finished reading, the callback will be executed.