Callback-based programming model:

Node.js relies heavily on callback functions to handle asynchronous operations. While callbacks provide a way to manage asynchronous code execution, they can lead to complex and nested code structures, often referred to as “callback hell.” This can make code harder to read, understand, and maintain. Although newer asynchronous patterns like Promises and async/await have been introduced to mitigate this issue, legacy codebases may still heavily rely on callbacks.