Browsers attempt to guess the importance of a resource when they discover it. For example, render-blocking stylesheets will be high priority, while a an asynchronous script can be loaded with a low priority. But sometimes it's not clear to the browser how important a resource is. For example, images are loaded with low priority by default. Most of them are likely below the fold or hidden somewhere in a nested menu. But that's not always what you want, as images that represent the primary page content should be loaded quickly. Priority hints solve this problem by providing the browser with additional information about the relative importance of a resource. For example, the fetchpriority attribute lets you mark specific important images as high priority.