History API: Change URLs Without Page Reloads

The History API gives you programmatic control over the browser's session history, forming the backbone of modern single-page apps (SPAs) by allowing URL changes without full page reloads. It's used to build client-side routers; `pushState()` changes the URL and adds a history entry, and your app listens for `popstate` events to render the correct view on back/forward navigation. The key footgun is that `pushState()` only changes the URL; your code must handle the `popstate` event to actually update the UI.