It's easy for "cookies" to accumulate in your web browser -- little bits of data left by websites you visit that identify you as someone the company knows. Sometimes they are a convenience, helping you get to your account more quickly or helping you see the kinds of offers you're most likely to be interested in. But they can be read from your browser for quite a while if you allow it, and you'd be surprised how many you may have. It's pretty easy to remove them from the "Settings" "Preferences" or "Options" panels of your web browser, and you'll have plenty of opportunities to accept more cookies.
Find out more about cookies on the Federal Trade Commission's website.