A cookie 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.
Most websites you visit will use cookies in order to improve your user experience by enabling that website to 'remember' you, either for the duration of your visit (using a 'session cookie') or for repeat visits (using a 'persistent cookie').
Cookies do lots of different jobs, like letting you navigate between pages efficiently, storing your preferences, and generally improving your experience of a website. Cookies make the interaction between you and the website faster and easier.
If a website doesn't use cookies, it will think you are a new visitor every time you move to a new page on the site – for example, when you enter your login details and move to another page it won't recognise you and it won't be able to keep you logged in.
If you don't wish to receive cookies, you can modify your browser so that it notifies you when cookies are sent to it or you can refuse cookies altogether. You can also delete cookies that have already been set.
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; the Help function within your browser should tell you how. Alternatively, you may wish to visit www.aboutcookies.org, which contains comprehensive information on how to do this on a wide variety of desktop browsers.