What is a law of nature?

Natural law can’t be broken, but can it be defined?
 Laws of nature are impossible to break and nearly as difficult to define. So, just what kind of necessity do they possess? Marc Lange, a distinguished Professor of Philosophy, reflects on why natural laws call for a philosopher’s logic as elegant as it is precise. “What philosophers aim to do is to figure out what sort of thing scientists are discovering when they discover the laws of nature. The philosopher’s aim is not to help scientists do their job. Instead, the philosopher’s aim is to better understand the job that scientists are doing.”