The amount of resistance (or cost) required to traverse a line from its origin node to its destination node or to make a turn (i.e., move from one arc through a node onto another arc). Resistance may be a measure of travel distance, time, speed of travel times the length, and so on. Higher impedance indicates more resistance to movement, with 0 indicating no cost. Often, a negative impedance value indicates a barrier. Impedance is used in network routing and allocation. An optimum path in a network is the path of least resistance (or lowest impedance).