A tracking cookie is a text file that a Web browser stores on a user's machine and that is used to track a user’s activity online. Tracking cookies are a specific type of cookie that can only track user activity through pages related to a site’s advertising, rather than establishing full surveillance capability through any website.
Techopedia explains Tracking Cookie
Some experts refer to tracking cookies as third-party cookies, because the party benefiting from the information is not the party that created the specific site visited. Various browsers allow users to delete or otherwise handle tracking cookies. This helps individual users protect themselves against the invasions of privacy that third-party tracking cookies can represent.
Within the general controversy around data collection on the Internet, many of those who use tracking cookies argue that the information collected is more demographic than personal and that it is used to help businesses make effective decisions about advertising and outreach. However, when individual identifiers like IP addresses and personal data are collected, there’s always a risk that they will be used inappropriately by data collectors. As a result, tracking cookies are likely to continue to be a controversial part of new online business models.