Without storing the unique authentication cookie in the browser, the website would require the user to authenticate themselves every time.

Can you order the steps of using a cookie for authentication?

Visit website that requires loginWebsite checks for authentication cookieWebsite checks if authentication cookie is validBypass login

Alright! That's why we don't need to enter a password each time we visit a site like Amazon or Facebook.

First, we visit the website, then the website checks for the cookie. If the cookie is valid, the login is bypassed.