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The article describes interesting audio effects that can be obtained by deforming the time and/or the frequency axis. Whilst discrete-time warping techniques were introduced in 1965, their interest in musical applications is fairly recent. Time warping aims at deforming the waveform or the envelope of the signal while frequency warping modifies its spectral content, e.g., by transforming an harmonic signal into an inharmonic one or vice versa. Effects obtained by warping often increase the richness of the signal by introducing detuning or fluctuation of the waveform. The sounds from natural instruments like piano and drums already possess this property.