process.nextTick() is a function in Node.js designed to schedule a callback function to be invoked in the next iteration of the event loop. 

It allows a callback to be executed immediately after the current operation but before the event loop continues. This makes it useful for ensuring that certain tasks, especially related to the execution context or I/O, are deferred until the next tick of the event loop. It is often used to break down large asynchronous operations into smaller, more manageable chunks.