Microsoft Knowledge Base Article 290333 contains the following summary:
This article describes the Platform for Privacy Preferences (P3P) project. P3P is a combined protocol and architecture designed to inform Web users of the data-collection practices of Web sites. Internet Explorer 6 supports the use of P3P version 1 Compact policies by Web sites to report their intended use of cookie information. The Compact policy information is used in combination with user preferences to determine whether Internet Explorer 6 will accept or block cookies from the Web site. The P3P specification and associated documents are located at the following World Wide Web Consortium Web site:
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