The
Fourier transform performs a decomposition of a
function of into its
sinusoidal components. As typically phrased in the language of
signal processing, the transformation decomposes a
signal – some given function of
time – into the
frequencies that make up the signal, akin to how a musical
chord can be expressed as combination of its constituent notes. While the Fourier transform is not limited to functions of
time in the literal sense, it is conventional to call the domain of the original function the
time domain and the domain of the transformed function the
frequency domain.