The optical methods of disperse media investigations are widely used today in many branches of physics from biophysics to environmental science and astronomy. Scatterers one meets in the fields are commonly known to have complex shape and structure, and many theoretical methods to treat the interaction of radiation with such particles have been developed. However, most of these approaches are still too computationally demanding for proper modelling of the optical properties of disperse media contain in non-spherical inhomogeneous scatterers. The main idea of the book is to provide a reader with thorough information and various tools to solve the problem. The authors plan to review the contemporary light scattering methods, to introduce efficient versions of the fast exact methods as well as of some approximate ones, to summarise theoretical studies of the applicability ranges of the methods and to formulate and illustrate the principia effects of scatterer shape and structure variations on the optical properties. As applications cosmic dust, atmospheric aerosols, nanosensors and other scatterers will be considered.