This document discusses the importance and techniques of personalization. Personalization allows websites to provide tailored experiences for individual users by testing different content variants and targeting users based on attributes. Testing involves randomly assigning users to different content variants and measuring key metrics like conversions to determine the most effective variants. Targeting uses rules to intentionally show different content to different users based on information known about them. Personalization requires defining variants, contexts, and goals and using reporting to understand what drives lift and inform future testing cycles to continuously improve personalization strategy. Tools like Acquia Lift can automate personalization through machine learning and integration with content management systems like Drupal.