This thesis analyzes personalization in search engines and how it impacts search engine optimization (SEO). It presents experiments on how personalization affects search rankings. The thesis proposes new SEO methods that leverage personalization. It contains 5 chapters that discuss personalized search operations, analyzing user behavior data, the effect of personalization on SEO metrics, an SEO guide, and a proposed system for global personalization. The thesis was supervised by Dr. Dariusz Król at the Faculty of Computer Science and Management.