A cookie is not a type of biscuit, it is a simple text file that is stored on your computer or mobile device by a website’s server and only that server will be able to retrieve or read the contents of that cookie. Each cookie is unique to your web browser. It will contain some anonymous information such as a unique identifier and the site name and some digits and numbers. It allows a website to remember things like your preferences or what’s in your shopping basket.
A few people find the idea of a website storing information a bit intrusive, particularly when this information is stored and used by a third party without them knowing. Although this is generally quite harmless you may not, for example, want to see advertising that has been targeted to your interests. If you prefer, it is possible to block some or all cookies, or even to delete cookies that have already been set; but you need to be aware that you might lose some functions of that website.
If you wish to restrict or block web browser cookies which are set on your device then you can do this through your browser settings; normally the Help function within your browser should tell you how. You may also wish to visit www.aboutcookies.org, which contains information on how to do this on a wide variety of desktop browsers.