Open DevTools, click on Application, and look at the left sidebar. Cookies, Local Storage, Session Storage, IndexedDB, Cache Storage, Shared Storage, Background Services… it’s a lot. I’ve seen senior developers reach for localStorage for everything — auth tokens, shopping carts, even megabytes of API responses — simply because it’s the one they know. That’s not always wrong, but it’s rarely the best choice. Let’s actually go through what each of these mechanisms does, where you’d find it in DevTools, and — more importantly — when you should reach for it instead of the other six options sitting right next to it.