This well-received third edition offers fresh perspectives on modern nanoscale problems, where fundamental science, technology, and computer modeling intersect. In addition to traditional computational techniques such as finite-difference schemes, finite element analysis, and Ewald summation, the book introduces the finite-difference calculus of Flexible Local Approximation MEthods (FLAME), which significantly improves numerical accuracy across a wide range of problems.Applications covered include long-range particle interactions in homogeneous and heterogeneous media, electrostatics of colloidal systems, wave propagation in photonic crystals, photonic band structure, plasmonic field enhancement, metamaterials, backward waves and negative refraction, cloaking, focusing beyond the diffraction limit, and transformation optics. This edition includes a brand-new chapter on topological photonics, along with updated sections on chiral metamaterials and homogenization theories. It has also been extensively revised and expanded to reflect recent developments. Much of the artwork has been significantly upgraded.