Cookies

In this section of the tutorial you'll learn how to use cookies to store information in the browser's client. You'll also learn how to read cookies from other sites, how to use cookies to gather sensitive information about users and how to use cookies to access programs on a user's hard drive.

Not really.

HTML cookies are one of the most misunderstood aspects of the Web. Nobody really seems to know exactly what they do, but everyone fears them. The truth of the matter is that HTML cookies are one of the most secure aspects of the online experience. Aside from the information that is sent with every HTML request, such as your Internet address, the page which referred you to the requested page and so forth, the only information that a cookie can gather from you is information that you explicitly provide.