I am assuming that our average reader will not know what a cookie is, so this is included in both data-cookies and pref-cookies.
A browser cookie is a small piece of data sent from a website and stored on your computer while you are browsing a website. When the you return to the same website in the future, the data stored in the cookie can be retrieved by the website to notify the website of your previous activity. Cookies are a common method used by web servers to know whether you are logged in to an account on a specific website or not.