The book "Theoretical Aspects of Local Search" offers a comprehensive collection of theoretical results in the field of local search, which has been successfully applied to a variety of optimization problems. It highlights the fundamental conceptual foundations, the general applicability, and the ability of local search to inspire new search paradigms. The authors, Wil Michiels, Emile Aarts, and Jan Korst, present the typical characteristics of combinatorial optimization problems associated with local search, as well as their relationship to complexity theory. Additionally, the combination with randomized search approaches is addressed, leading to a variety of interesting theoretical results. This book is the first comprehensive compilation of these results and provides readers with a coherent overview of the achievements in this challenging research field.