In mathematics, a filter is a subset of power set with certain properties. See filter (mathematics).
A filter is a short-form of mail filter.
An electronic filter is an electrical circuit whose frequency response or transfer function is non-uniform. In other words, its gain or attenuation depends on frequency.
An analog filter is a form of filter (usually electronic) that uses analog circuitry in its implementation.
A digital filter is an algorithm for processing numeric data, and which can also be used in digital signal processors to function in a similar way to an electronic filter. Digital filters are now used in many modern appliances, such as CD players, radio tuners, TVs etc.
An audio filter is a type of filter that is used for processing audio signals in appliances such as CD players, synthesizers or sound effects.
A 1990s industrial rock band is called Filter.
An optical filter removes/only passes certain wavelengths of light, e. g. Infrared filter, ND filter, UV filter
See also: Glossary of filter terms\n
