What are the two families of circles and arcs that make up a Smith chart?

The grid lines on a Smith chart represent the real and imaginary parts of complex impedance. The 'real' part is resistance, plotted as complete circles, while the 'imaginary' part is reactance, plotted as intersecting arcs. Together, these two families of curves allow you to pinpoint any complex impedance value on a single plane. Distractors like 'inductance and capacitance' are incorrect; although reactance is caused by inductors and capacitors, the chart's coordinate system plots the resulting reactance in ohms, not the component values themselves.