Explain the difference between cookies, sessionStorage, and localStorage.

localStorage and sessionStorage are web storages accessible via the DOM, whereas cookies are small text files sent with HTTP requests.

Main differences:

Property	cookies	localStorage	sessionStorage
Storage size	Up to 4 KB	Up to 5-10 MB (depends on browser)	Up to 5-10 MB (depends on browser)
Server transmission	With each HTTP request	No	No
Lifespan	Manually set (can be indefinite)	Stored until browser cache is cleared	Stored until tab/browser is closed
Access	Client and server	Client only	Client only

Usage:

• cookies: Store session information (identifier), personalized user settings, shopping cart contents in online stores (until browser is closed).
• localStorage: Long-term storage of user settings (theme, language), interface states, client-side data caching.
• sessionStorage: Store information specific to the current session, such as form data or temporary settings.

API examples:

// cookies (via document.cookie)
document.cookie = "username=John Doe; expires=Thu, 18 Dec 2025 12:00:00 UTC; path=/";
const cookies = document.cookie;

// localStorage
localStorage.setItem("name", "Alice");
const name = localStorage.getItem("name");
localStorage.removeItem("name");
localStorage.clear(); // Removes all entries

// sessionStorage
sessionStorage.setItem("lastVisit", new Date().toISOString());
const lastVisit = sessionStorage.getItem("lastVisit");
sessionStorage.removeItem("lastVisit");
sessionStorage.clear(); // Removes all entries