What is the shape of the waveform of the electricity supplied from a household receptacle?

The alternating current (AC) supplied by utility grids to household receptacles is generated by rotating magnetic machinery. The natural mathematical shape produced by a generator rotating at a constant speed through a magnetic field is a smooth, continuous sine wave (sinusoidal). Other waveforms, such as square, modified square, or pulse waves, involve abrupt, sharp changes in voltage. While these jagged shapes are common in digital circuits or inexpensive DC-to-AC inverters, they do not represent the clean, continuous oscillation of standard grid electricity.