This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book presents an integrative perspective on the meaning and clinical applications of the concept of intersubjectivity in psychoanalysis. It proposes a model that takes into account the diverse sources of intersubjectivity, including contributions from philosophy, neuroscience, and infant research. The book emphasizes the field of semiotics, which provides a common foundation for different models of psychoanalytic practice, all of which involve the exchange of signs between subjects. It traces the concept of intersubjectivity from its historical developments in several disciplines, each viewing human interaction through different frames. The book also provides three case vignettes that illustrate intersubjective functions of affect in clinical situations. It explores the recurring question of whether psychoanalysis can be compared productively to the study of a text. It reviews the semiotic approach and explains its key concepts, primarily using the work of C. S. Peirce.