High-voltage overhead lines have been the backbone of power grids for more than 125 years. This chapter begins with a discussion of the external loads on overhead lines and their components, from material selection to manufacturing processes to dimensioning. This is followed by the sub-chapter on conductors, including sag calculation, state equation, monitoring, conductor vibrations, and high-temperature conductors. The focus for insulators is on porcelain, glass, and composite insulators, while for fittings it is on conductor clamps and vibration dampers. Also, overhead line structures, from classic steel lattice towers to compact lines often used today, are discussed in detail along with their foundations. The chapter concludes with a discussion of line construction and maintenance, as well as the upgrading and uprating of lines. Many calculation examples and an extensive bibliography round off this chapter.