In Node.js, event-driven programming means as soon as Node starts its server, it initiates its variables, declares functions and then waits for an event to occur. It is one of the reasons why Node.js is pretty fast compared to other similar technologies.

In Node.js, event-driven programming is a paradigm where the flow of the program is determined by events that occur asynchronously. These events could be triggered by various sources such as user actions, file system operations, network requests, timers, etc.

The key components of event-driven programming in Node.js include:

Event Emitters: Objects that emit named events, which can be listened to by event listeners.
Event Listeners: Functions that are executed when a specific event occurs. They are attached to event emitters to handle the emitted events.
Event Loop: Node.js employs an event loop to handle asynchronous operations efficiently. It continuously listens for events and executes associated callback functions when an event occurs, allowing the program to remain responsive.
Callbacks: Functions that are passed as arguments to asynchronous operations. They are invoked once the operation completes or an event is triggered, allowing non-blocking execution of code.

In summary, event-driven programming in Node.js enables efficient handling of asynchronous tasks by leveraging event emitters, event listeners, the event loop, and callbacks to manage the flow of the program.