This book thoroughly analyzes the fundamental problem of programmable interconnect design in FPGAs. Recent changes in fabrication technology have caused a renewed interest in this problem that was formerly considered largely solved. Besides presenting some of the most recent research results directed towards resolving the difficulties of programmable interconnect design in scaled technologies, the author also gives a modern introduction to programmable interconnect design in general, covering related topics such as broader FPGA architecture, CAD, and Networks on Chip, enabling practitioners from other fields to understand the significance and implications of this important problem.