Wirebook › Glossary › Third-party cookie
What is a third-party cookie?
In one sentence: A cookie from a company other than the website you are on, such as an advert tucked inside the page. It can link your visits across many websites, so many browsers block it.
A little more
A first-party cookie comes from the website you are actually visiting, like a shop remembering your basket. A third-party cookie comes from a different company whose piece is tucked inside the page: an advert, a share button or a video player.
Because the same company is tucked inside thousands of websites, one cookie of its own can link your visits together into a list of your interests. That is why many browsers now block third-party cookies or give each website its own separate jar, so the notes can't be joined up.