Collaborative filtering infers interests from patterns in multiple users’ preferences or behavior. Used as a privacy-enhancing technology, it can personalize content without storing large amounts of personal data, supporting engagement while reducing intrusive tracking. section 2.3.4
Figure 2.7 Engagement and activation layer overview
Places privacy-preserving personalization within the engagement and activation layer, alongside consent, transparency, and minimal data collection. section 2.3.4



