Cache headers can&#x27;t ensure that your site works offline—that&#x27;s a big difference.<p>There&#x27;s Application Cache, but it&#x27;s treacherous and deprecated.<p>Service Workers get near-total control over outgoing HTTP requests, which has many various uses.<p>Then there are the coming features. You&#x27;ll be able to push messages to your service worker even if your site isn&#x27;t open in any tabs, for example.