Video narration
When you record a chord on your phone, what is that messy wave made of? Your phone turns the sound into measurements taken at even time steps. Together, they trace one changing waveform, but that curve isn't one indivisible sound. The chord is a mix of frequencies layered together. But the waveform isn't the whole story. The Discrete Fourier Transform, or DFT, compares those samples with a fixed set of frequency waves. Each comparison gives a number showing how strongly that frequency matches. Its size indicates strength; it also carries phase information. The results line up as frequency bins, individual slots in a frequency map, not a list of named notes. A real frequency can fall between slots, spreading its strength across nearby bins. So what was inside your recorded chord? The DFT shows how strongly each tested frequency is present, turning the waveform into a frequency map.