What is a cookie?
A cookie is a piece of data that is stored by a website within an internet browser. This data is then sent back to the same website by the browser. Cookies act as a reliable device for websites to remember things that an internet browser has done in the past – this includes clicking particular buttons, log in details, or having read pages on that site previously.
Typically, a cookie contains information such as the domain from which the cookie comes from, a value which is usually a random unique number as an identifier and the lifetime (expiry) of the cookie.