The read-only sessionStorage property accesses a session Storage object for the current origin. sessionStorage is similar to localStorage; the difference is that while data in localStorage doesn't expire, data in sessionStorage is cleared when the page session ends.| MDN Web Docs
The localStorage read-only property of the window interface allows you to access a Storage object for the Document's origin; the stored data is saved across browser sessions.| MDN Web Docs
Service workers essentially act as proxy servers that sit between web applications, the browser, and the network (when available). They are intended, among other things, to enable the creation of effective offline experiences, intercept network requests, and take appropriate action based on whether the network is available, and update assets residing on the server. They will also allow access to push notifications and background sync APIs.| MDN Web Docs