Book excerpt: This book provides an overview of electronic and optical properties of graphite-related systems. It presents a well-developed and up-to-date theoretical model and addresses important advances in essential properties and diverse quantization phenomena. Key features include various Hamiltonian models, dimension-enriched carbon-related systems, complete and unusual results, detailed comparisons with the experimental measurements, clear physical pictures, and further generalizations to other emergent 2D materials. It also covers potential applications, such as touch-screen panel devices, FETs, supercapacitors, sensors, LEDs, solar cells, photodetectors, and photomodulators.