This chapter discusses phasors without explicitly including the time exponential. Power systems are 3-phase systems. This means that the voltages and currents come in triples. The voltages and currents in 3 phases are shifted in time relative to each other by a third of a cycle. The significance of these systems of phasors is that any 3-phase collection of phasors can be written as sum of phasors, one from each of these systems. The components of such a sum are called symmetrical components. This makes it possible to analyze an unbalanced 3-phase system by separately analyzing symmetric sequence systems and then adding the results. The virtue of using symmetrical components is that an unsymmetrical 3-phase set of phasors can be analyzed in terms of 3 symmetrical systems of phasors. Since the component systems are symmetrical, only one phase from each symmetrical system need be analyzed, in same manner that needs only consider one phase of a conventional balanced 3-phase system.