A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic waves or acoustic waves, as well as electric power transmission. This book presents current research data from across the globe in the study of transmission lines, including fault location fundamentals in transmission and distribution systems; optical fibres used for terrestrial and submarine transmission systems; transmission pole dynamics and design; the impacts of priority service on transmission investment using a mathematical programming model; impedance matching by segmented transmission lines; and wave propagating in the magnetically insulated transmission line.