The term filter may refer to:

• A device to separate mixtures. See filter (chemistry), filter (water), filter (air), pneumatic filter.
• A device to remove or block certain wavelengths (colors) of light. See filter (optics), filter (photography), infrared filter
• A computer program to process a data stream. See filter (software), filter (Unix), mail filter, printer filter, Internet filter, lameness filter.
• ADSL Broadband filter, blockes interferences between regular phone voice signals and broadband signals. Protocols & Specifications ITU G.992.1 (G.DMT), ITU G.992.2 (G.Lite). It can be wall-mount or in-line (integrated or not in a DSL router/modem). Filter installation is generally required on each phone jack. See also splitter, RJ-11 and image.
• An electronic or mechanical device, or mathematical algorithm, for affecting the harmonic content of signals. See electronic filter, signal processing, audio filter.
• In mathematics, a certain kind of subset of a partially ordered set. See filter (mathematics)

In chemistry and common usage, a filter is device (usually a membrane or layer) that is designed to block certain objects or substances whilst letting others through. ... A filter is a device which removes impurities from water by means of a fine physical barrier. ... An air filter is a device which cleans dirty air. ... A pneumatic filter is a device which removes contaminants from the compressed air stream. ... Coloured and Neutral Density filters An optical filter is a device which selectively transmits light having certain properties (often, a particular range of wavelengths, that is, range of colours of light, or polarizations), while blocking the remainder. ... In photography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. ... An infrared filter is a filter to remove visible light and only pass infrared light in different wavelenghts. ... A filter is a computer program to process a data stream. ... In UNIX and UNIX-like operating systems, a filter is program that gets most of its data from standard input and writes its main results to standard output. ... A mail filter is a piece of software which takes an input of an email message. ... An Internet Filter is a piece of software installed by overprotective parents that cant actually be bothered to supervise their children online, it makes sure that sites promoting hate crimes to gays and minorities are not blocked, while stripping access to websites for Sesame Street. ... Lameness filters are textbased filters used by SlashCode-based websites to stop junk comments from being posted in response to stories. ... Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. ... Broadband in general refers to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission. ... In telecommunications, ITU G.992. ... ADSL in Australia started off as ITU G.992. ... Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. ... In-line expansion or inlining for short is a compiler optimization which expands a function call site into the actual implementation of the function which is called, rather than each call transferring control to a common piece of code. ... Look up Jack in Wiktionary, the free dictionary Jack has many meanings: Names Jack (name), originally a nickname for John. ... A split-finger fastball or splitter, is a pitch in baseball and a variant of the straight fastball. ... RJ-11 (Registered Jack 11) is a physical interface often used for terminating twisted pair type cables. ... Electronic filters are electronic circuits which perform signal processing functions. ... Signal processing is the processing, amplification and interpretation of signals. ... An audio filter is a type of filter used for processing sound signals. ... A is a subset of B, and B is a superset of A. In mathematics, especially in set theory, a set A is a subset of a set B, if A is contained inside B. Every set is a subset of itself. ... In mathematics, especially order theory, a partially ordered set (or poset for short) is a set equipped with a partial order relation. ... In mathematics, a filter is a special subset of a partially ordered set. ...

See also

• Filtration
• Affective filter, a type of learning blockage.
• Conversion
• Filter coffee, a hot drink
• Filter feeder, an animal that strains food particles from water
• Filter (band), a 1990s industrial rock band
• Filter (television), a show on the G4 channel
• Filter (magazine), an off-beat indie music magazine
• Philter, a magical charm