Per definition, a third-party cookie is a cookie that another website than the one the user visits creates. The user’s computer stores the third-party cookies. This allows for the sharing of data to a third-party.
The shared data allows for advisers to track the user’s browsing history. The default setting in a Web browser generally allows third-party cookies. However, the user can block them. The EU continuously debates the usage of third-party cookies. The debate includes the information to give to the users and how the user can edit the settings for each domain. Cases from CJEU provides further guidance.