How electromagnetic radiation such as light is scattered or absorbed by media is used in many fields as it can provide information on the size, shape, number, and dynamics of particles or objects. It is key to fields as diverse as physical chemistry, materials science, nanotechnology, microbiology, astronomy, atmospheric sciences and radar. This is not purely an academic concern, most aerosol mass in the atmosphere, including entrained mineral dust, volcanic ash, and soot consists of particles with irregular shapes and the way they scatter and absorb light has implications for many climate models. One new approach considers the scattering in reciprocal or Q-space. Q-space analysis has been used extensively in the fields of small angle x-ray and neutron scattering but developments in scattering, in general, and light scattering in particular, are relatively recent. This book provides a thorough overview of how particles of any size or shape scatter and absorb light. Its conceptual basis is unique and founded on the fact that light is first and foremost a wave and then also an electromagnetic wave. Thus the wave phenomenon of diffraction underlies all scattering, and the electromagnetic character of light causes the scattering to evolve away, in a systematic manner, from the diffraction limit. The mathematics of diffraction is the Fourier transform which links real space to reciprocal space, which we call Q-space. The Fourier variable q is related to the scattering angle in experiments so that with our Q-space perspective, we plot scattering data versus q, rather than the angle. This modest change allows hitherto unseen patterns and functionalities in scattering that unifies scattering of all shapes. Key features An accessible introduction to a coherent physical description of scattering Emphasis on interpretation and applications Written by a pioneering researcher in the subject Self-contained includes relevant background physics and maths A fresh, novel way to view the scattering of light by particles