Def. Simple ’text files’ that contain two pieces of information: a site name and unique user ID . Upon visiting a site (that uses cookie) for the first time, a cookie is downloaded onto your device. That way when you visit the site again, it knows that you have been there before and sends pop up recommendations, ads, etc. based on it’s record of your activity the first time you were there.
Cookies may record how long you spend on each page of the site, what links you click, even your preferences for page layouts and colour schemes.