The handbook of heuristics consists of five main parts: search strategies, local search, metaheuristics, analysis and implementations, and applications. They cover from search methods and methodological aspects, such as matheuristics, the exciting field in which mathematical programming is combined with heuristics, to applications that provide the practitioner with a description of some relevant optimization issues in a number of specific application areas, such as scheduling, vehicle routing, or network optimization. The first edition of the Handbook of Heuristics was published in 2018 and contained 47 chapters. In this second edition, the authors revised 30 of them to include new developments in the area that appeared in the last few years. In particular, the reader may find 14 chapters in search strategies, including a new chapter on deep learning, 4 in local search, 14 in metaheuristics, 5 in analysis and implementations, and 24 in applications. The inclusion of 14 new chapters makes this second edition even more comprehensive, totaling 61 chapters.