Local credentials and cookies

When one logs out of an unregistered Stackexchange account, one is presented with the message

You’re an unregistered user. We only know who you are through your browser cookies. If you log out before registering, this account will be irretrievably lost! Clicking Log Out will clear all local credentials in your browser开发者_如何学Python.

What does this mean? Does it mean that Stackexchange does not log my access? (i.e. does not store my IP address...?) Also, could someone explain in layman terms what "cookies" and "local credentials" are?

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When you arrive at StackOverflow as an anonymous user, the site stores a "cookie" on your computer, which contains the information required to identify the account that was just created for you. A cookie is just a piece of string data that is stored on your computer, which can be accessed by the website that created it.

The cookie will stay on your computer, storing these "local credentials" that were created, so when you go back to StackOverflow, the site will see the cookie, and will use that data to "remember" who you were.

When you "log out", the cookie will be deleted. Now, when you visit StackOverflow again, it can't locate the cookie, so it doesn't know who you are. And if you haven't registered, then there's no way to log back in, because the only credentials the site had for you were stored on your computer in a cookie that no longer exists.