In
electronics,
control systems engineering, and
statistics, the
frequency domain refers to the analysis of
mathematical functions or
signals with respect to
frequency, rather than time. Put simply, a
time-domain graph shows how a signal changes over time, whereas a frequency-domain graph shows how much of the signal lies within each given frequency band over a range of frequencies. A frequency-domain representation can also include information on the
phase shift that must be applied to each
sinusoid in order to be able to recombine the frequency components to recover the original time signal.