This chapter provides an overview of the evolution of microelectronics and relates it to the contents of this book, namely electromigration (EM) issues that arise during integrated circuit (IC) design and how such issues are best avoided and managed. The increasing importance of EM in IC design can be understood in the context of two broad developments that we explore in this chapter. First, we show that present and future development in the semiconductor industry is moving toward ever higher current densities. And second, we discuss how boundary values for approved operation in the IC’s interconnect, such as maximum tolerable current densities, are shrinking due to smaller structure sizes. As a consequence of these two fundamental and contradictory developments, we show how EM issues are becoming a crucial and, indeed in many cases, critical, IC design criterion. We introduce approaches in technology, modeling, and design to face this growing challenge. The chapter concludes with an overview of the book’s more detailed content.