Fast Fourier Transform (FFT): Decomposes continuous time-domain waveforms into discrete harmonic frequency bins:
1. Nyquist Limit: Maximum resolvable frequency is f_nyquist = f_sample / 2 (~22.05 kHz for standard 44.1 kHz audio contexts).
2. Spectral Centroid: Indicates perceptual "brightness" as the amplitude-weighted mean frequency: C = Σ(f_k · A_k) / Σ A_k.
3. Modes: Spectrum Bars, Oscilloscope Waveform, Radial Polar Bloom, and Spectrogram Waterfall.