Ellipsometry, a measurement technique based on phase and amplitude changes of polarized light, is becoming popular in a widening array of applications because of increasing miniaturization of integrated circuits, breakthroughs in knowledge of biological macromolecules deriving from DNA and protein surface research, materials physics design of thin film multilayer surfaces, composite and smart materials, and materials engineering at the nano scale. Ellipsometry does not contact or damage samples, and is an ideal and precise measurement technique for determining optical and physical properties of materials at the nano scale. Contemporary applications cover widest spectral regions from the terahertz domain to ultra short wavelengths, addressing bound and unbound charge excitations in complex layer structures, unveiling critical foundation parameters of new materials, or controlling intricate layer structures in real time during growth, for example. Insight into state-of-the art ellipsometry characterization approaches, including data acquisition and analysis procedures, will be given by surveys of science and technology of ellipsometry for scientists and researchers at the forefront of nanotechnology, accompanied by a sound introductory sequence into the basics of this critical subject.