"Let's start by defining both cookies and how they are
used to track your online behavior.
"Cookies are small, plain-text files that reside on your
computer and are managed by a web browser. If you have multiple web
browsers installed on a single computer, each one maintains its own
independent cache of cookies.
"As web pages are downloaded to a computer, cookies typically
come along for the ride. Likewise, as you make requests for new web
pages, your web browser may upload a cookie as part of the web page
request.
"Cookies that come from the web page you are viewing (the one
whose address is displayed by your web browser) are referred to as
“first party” cookies. Those that come from other
sources, be they ads on the web page or small independent pages
(IFRAMES) included in what appears to you to be a single page, are
"third party" cookies."