This article provides an overview of high voltage direct current (HVDC) and high voltage alternating current (HVAC) power transmission alternatives. The use of HVDC systems currently represents an efficient alternative under certain conditions, mainly due to reduced converter costs, improved power system flexibility and higher economic efficiency for long distances and, in particular, when it is relevant for power transmission over submarine or subway cables. Therefore, this paper describes the overview of the two alternatives, both from a technical and economic point of view