Fourier transform refers to transforming signals between the time domain and the frequency domain. As a standard method of data analysis, it is utilized for analyzing a variety of data including voice, vital reactions and digital images.
When signals are shown in a graph, if the graph's horizontal axis expresses time, it provides the time domain; if the horizontal axis expresses frequency, it constitutes the frequency domain. The time domain illustrates changes in signals over the passage of time with a waveform. The frequency domain extracts frequencies from the waveform and indicates which frequencies are included in the signals. Changing the expression through Fourier transform makes it easier to grasp the characteristics of signals.