What is the difference between localStorage and sessionStorage?

Both are Web Storage APIs that let you store string key/value pairs in the browser, scoped to an origin. sessionStorage is tab-scoped and typically cleared when the tab or window session ends. localStorage persists until the user or code clears it (or storage is reset), still per origin. Neither is safe for secrets: any script on the page can read them, so treat them as convenience storage, not authentication guarantees.

sessionStorage.setItem('draft', text);
localStorage.setItem('theme', 'dark');
const theme = localStorage.getItem('theme');

Start simple: try this concept in a tiny project before moving to advanced tools.