The main objective is to present the key ideas of seismic interferometry and illustrate them with seismic examples from marine data, land data, and synthetic data. MATLAB exercises will be presented that educate the user about the benefits and pitfalls of interferometric imaging. Examples will be presented that use interferometry for 2D deconvolution, data extrapolation, data interpolation, super-stacking, passive seismology, surface-wave interferometry, and super-illumination.