A Cookie is a small piece of information that is automatically stored (by a Web server) on a user's hard drive. The main purpose of cookies is to identify the user. That is why cookies might contain information such as login, password, online shopping cart information, or other data used by websites. Cookies hold information that can be retrieved by other web pages on the site. There is also a type of cookies that have an expiration date and are automatically deleted after the specified period of time.