When used appropriately, cookies can be an invaluable tool for a webmaster. You can use them to simplify sign-on procedures, set up shopping carts, and provide individual users with more personalized information on your site. Cookies can help you incorporate those features into your site. Cookies are stored in a text file whose exact name and location depend on the user's operating system and browser. Web servers use the stored information to identify the particular user by requesting authentication information from the user.
Cookies are browser-specific.
A cookie set when you browse in Netscape Navigator will not be read if you visit the same site again using Internet Explorer. Cookies cannot store any personal information about the user that the user doesn't voluntarily supply to the Web site. Cookies do not contain viruses. A server can only get data from the cookie it wrote to the cookie file - it can't go fishing for information on the hard drive. Links take the user to a personalized page that highlights products based on their personal profile.