Consulting has become a service that permeates all areas of life in modern society, characterized by its uncertainties. A high demand for consulting has led to a growing range of consulting services that cater to all ages and life situations. This textbook develops a comprehensive system that serves as a guide in an increasingly complex field. Just as diverse as the occasions for consulting are the various approaches to it. The foundation of the book is a consulting model that systematically differentiates theories, definitions, conceptual distinctions, processes, methods, and legal questions. The different forms of consulting are presented based on this model, with practical examples illustrating each description.