Aliasing is a form of distortion which can occur during the conversion of analog signals into digital. If the input signal is more than one half the sampling rate, only portions of the signal will be present when the system samples the waveform. A false image of the waveform based on the components that were actually sampled, is created.
A system which samples at 48 kHz can correctly process signals of up to 24 kHz. To remove signals above the Nyquist frequency, all A/D converters employ anti-aliasing filters. Many digital audio devices employ oversampling A/D converters to allow the anti-aliasing filter to be performed in the digital domain.