Chaining Promises by using multiple .then calls allows you to perform a series of asynchronous operations one after another, passing the result of each operation to the next. This approach improves code structure significantly compared to deeply nested callbacks, which often lead to complex and hard-to-read code known as callback hell. With Promise chaining, you can write asynchronous flows that are easier to follow and maintain, since each step is clearly defined and the flow of data between steps is explicit. This makes your code more readable, less error-prone, and easier to debug, especially as your asynchronous logic grows in complexity.