A cookie is a small piece of data or message that is sent from an organisation's web server to your web browser and is then stored on your hard drive. Cookies can't read data off your hard drive or cookie files created by other sites, and do not damage your system.
However, you can reset your browser so as to refuse any cookie or to alert you to when a cookie is being sent. Web browsers allow you to control cookies stored on your hard drive through the web browser settings. To find out more about cookies, including what cookies have been set and how to manage and delete them, visit http://www.allaboutcookies.org.