This book reviews the optical spectra of phthalocyanines and related compounds. The book also provides a theoretical background to distinguish their spectra from those of porphyrins as graphically as possible and without mathematicization. Phthalocyanines are tricky because their spectra behave like the sea-god Proteus: depending on conditions they sometimes can be very misleading. Therefore, those who have worked with these compounds for the first time, even educated professional researchers and engineers, may have been embarrassed by the deceptive behavior of phthalocyanines and could have,...