This introductory chapter presents an overview of the role of semiotic issues in the teaching and learning of mathematics, as these issues are characterized and elaborated in the chapters of this monograph. Several threads are represented in the four sections of this book: the evolving sociocultural perspective is addressed in Sects. 1 and 4; Sect. 2 addresses linguistic and textual aspects of signification, and Sect. 3 represents Peircean perspectives that were recognized as important in our field more than two decades ago, which continue to have relevance.