A cookie consists of information sent by a web server to a web browser and is stored by the browser. The information is then sent back to the server each time the browser requests a page from the server. This enables the web server to identify and track the web browser.
Third parties who provide web services to us may also send you cookies.
Most browsers allow you to reject all cookies, whilst some browsers allow you to reject just third party cookies. For example, in Internet Explorer you can refuse all cookies by clicking Tools, Internet Options, Privacy, and selecting Block all cookies using the sliding selector. Blocking all cookies will, however, have a negative impact upon the usability of many websites.