This book presents cutting-edge research advances in the rapidly growing areas of nanoantennas and plasmonics as well as their related enabling technologies and applications. It provides a comprehensive treatment of the field on subjects ranging from fundamental theoretical principles and new technological developments, to state-of-the-art device design, as well as examples encompassing a wide range of related sub-areas. The content of the book also covers highly-directive nanoantennas, all-dielectric and tuneable/reconfigurable devices, metasurface optical components, and other related topics. Intended to provide valuable information for researchers and graduate students in electromagnetics, antennas and propagation, coverage includes the following topics: optical properties of plasmonic nanoloop antennas; passive and active nano cylinders; coherent control of light scattering; time domain modeling with the generalized dispersive material model; inverse-design of plasmonic and dielectric optical nanoantennas; multi-level atomic systems for modeling nonlinear light-matter interactions; nonlinear multipolar interference: from non-reciprocal directionality to one-way nonlinear mirrors; plasmonic metasurfaces for controlling harmonic generations; optical nanoantennas for enhanced THz emission; active photonics based on phase-change materials and reconfigurable nanowire systems; and nanofabrication techniques for subwavelength optics.