In electronics, a signal edge is a transition of a digital signal from low to high or from high to low: * A rising edge (or positive edge) is the low-to-high transition. * A falling edge (or negative edge) is the high-to-low transition. In the case of a pulse, which consists of two edges: * The leading edge (or front edge) is the first edge of the pulse. * The trailing edge (or back edge) is the second edge of the pulse.