A low-pass filter is an electronic filter that passes low-frequency signals but attenuates signals with frequencies higher than the cutoff frequency.
The actual amount of attenuation (reduction of amplitude) for each frequency varies from filter to filter. It is sometimes called a high-cut filter, or treble cut filter when used in audio applications. Low-pass filters exist in many different forms, including electronic circuits (such as a hiss filter used in audio), anti-aliasing filters for conditioning signals prior to analog-to-digital conversion, digital filters for smoothing sets of data, acoustic barriers, blurring of images, and so on.
Source: Wikipedia.
