Filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...

is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to:

Science and technology

Computing

Filter (higher-order function) In functional programming, filter is a higher-order function that processes a data structure (usually a list (data structure), list) in some order to produce a new data structure containing exactly those elements of the original data structure for ...

, in functional programming *

Filter (software) A filter is a computer program or subroutine to process a stream, producing another stream. While a single filter can be used individually, they are frequently strung together to form a pipeline. Some operating systems such as Unix are rich with f ...

, a computer program to process a data stream *

Filter (video) A video filter is a software component that performs some operation on a multimedia stream. Multiple filters can be used in a chain, known as a '' filter graph'', in which each filter receives input from its upstream filter, processes the inp ...

, a software component that performs some operation on a multimedia stream * Information filtering system **

Email filtering Email filtering is the processing of email to organize it according to specified criteria. The term can apply to the intervention of human intelligence, but most often refers to the automatic processing of messages at an SMTP server, possibly ap ...

, the processing of email to organize it according to specified criteria *

Content-control software An Internet filter is software that restricts or controls the content an Internet user is capable to access, especially when utilized to restrict material delivered over the Internet via the Web, Email, or other means. Such restrictions can be appl ...

also known as an Internet filter *

Wordfilter A wordfilter (sometimes referred to as just "filter" or "censor") is a script typically used on Internet forums or chat rooms that automatically scans users' posts or comments as they are submitted and automatically changes or censors particula ...

, a script typically used on Internet forums or chat rooms *

Berkeley Packet Filter The Berkeley Packet Filter (BPF; also BSD Packet Filter, classic BPF or cBPF) is a network tap and packet filter which permits computer network packets to be captured and filtered at the operating system level. It provides a raw interface to da ...

, filter expression used in the qualification of network data *

DSL filter A DSL filter (also DSL splitter or microfilter) is an analog low-pass filter installed between analog devices (such as telephones or analog modems) and a plain old telephone service (POTS) line. The DSL filter prevents interference between su ...

, a low-pass filter installed between analog devices and a telephone line * Helicon Filter, a raster graphics editor *

Filter (large eddy simulation) Filtering in the context of large eddy simulation (LES) is a mathematical operation intended to remove a range of small scales from the solution to the Navier-Stokes equations. Because the principal difficulty in simulating turbulent flows comes fr ...

, a mathematical operation intended to remove a range of small scales from the solution to the Navier-Stokes equations *

Kalman filter In statistics and control theory, Kalman filtering (also known as linear quadratic estimation) is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, to produce estimates of unk ...

, an approximating algorithm in optimal control applications and problems *

Filter (social media) Filters are digital image effects often used on social media. They initially simulated the effects of Photographic filter, camera filters, and they have since developed with Facial recognition system, facial recognition technology and computer-gen ...

, an appearance-altering digital image effect for social media

Device

Filter (chemistry) Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter ...

, a device which separates solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass ** Filter (aquarium), critical components of both freshwater and marine aquaria **

Filter paper Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases. The raw materials are typically different pulp (paper), paper pulps. The pulp may be ...

, a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air **

Air filter A particulate air filter is a device composed of fibrous, or porous materials which removes particulates such as smoke, dust, pollen, mold, viruses and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbo ...

, a device composed of fibrous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air **

Oil filter An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsatur ...

, a filter to remove contaminants from engine oil, transmission oil, lubricating oil, or hydraulic oil ** Pneumatic filter, a device which removes contaminants from a compressed air stream **

Water filter A water filter removes impurities by lowering contamination of water using a fine physical barrier, a chemical process, or a biological process. Filters cleanse water to different extents, for purposes such as: providing agricultural irrigation, ...

, removes impurities from water by means of a fine physical barrier, a chemical process or a biological process **

Cigarette filter A cigarette filter, also known as a filter tip, is a component of a cigarette, along with cigarette paper, capsules and adhesives. Filters were introduced in the early 1950s. Filters may be made from plastic cellulose acetate fiber, paper or ...

, a part of a cigarette intended to filter the smoke inhaled by a smoker **

Coffee filter Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially av ...

, a utensil used to separate coffee grounds from liquid coffee **

Fuel filter A fuel filter is a filter used to screen out foreign particles or liquids from the fuel. Most internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an o ...

, found in most internal combustion engines **

Filtration (wine) In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine is removed before bottling. This matter may include dead yeast cells ( lees), bacteria, tartrates, proteins, pectins, various tanni ...

Sieve A sieve (), fine mesh strainer, or sift is a tool used for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet m ...

or macroscopic filter, a device for separating wanted elements from unwanted material

Mathematics

Filter (mathematics) In mathematics, a filter or order filter is a special subset of a partially ordered set (poset), describing "large" or "eventual" elements. Filters appear in order and lattice theory, but also topology, whence they originate. The notion dual ...

, a special subset of a partially ordered set. *

Filter (set theory) In mathematics, a filter on a set X is a family \mathcal of subsets such that: # X \in \mathcal and \emptyset \notin \mathcal # if A\in \mathcal and B \in \mathcal, then A\cap B\in \mathcal # If A\subset B\subset X and A\in \mathcal, then B\in ...

, a special family of subsets that forms an (order theoretic) filter with respect to set inclusion *

Filters in topology In topology, filters can be used to study topological spaces and define basic topological notions such as convergence (topology), convergence, Continuous map (topology), continuity, Compact space, compactness, and more. Filter (set theory), Filt ...

, the use of collections of subsets to describe convergence. *

Filtering problem (stochastic processes) In the theory of stochastic processes, filtering describes the problem of determining the state of a system from an incomplete and potentially noisy set of observations. For example, in GPS navigation, filtering helps estimate a car’s true posit ...

, a mathematical model for a number of filtering problems in signal processing and the like. *

Filtration (mathematics) In mathematics, a filtration \mathcal is, informally, like a set of ever larger Russian dolls, each one containing the previous ones, where a "doll" is a subobject of an algebraic structure. Formally, a filtration is an indexed family (S_i)_ of ...

, an indexed set of subobjects of a given algebraic structure S.

Optics

Optical filter An optical filter is a device that selectively transmits light of different wavelengths, usually implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings. The optic ...

, selectively transmits light of different wavelengths **

Interference filter An interference filter, dichroic filter, or thin-film filter is an optical filter that Reflection (physics), reflects some wavelengths (colors) of light and transmits others, with almost no absorption (optics), absorption for all wavelengths of i ...

, reflects one or more spectral bands or lines and transmits others, while maintaining a nearly zero coefficient of absorption for all wavelengths of interest **

Dichroic filter In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are ab ...

, a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors ** Hydrogen-alpha filter, an optical filter that transmits a narrow bandwidth of light centred on the H-alpha wavelength **

Photographic filter In photography and cinematography, a filter is a camera accessory consisting of an optical filter that can be inserted into the optical path. The filter can be of a square or oblong shape and mounted in a holder accessory, or, more commonly, a ...

, a camera accessory consisting of an optical filter that can be inserted in the optical path ** Infrared cut-off filter, designed to reflect or block mid-infrared wavelengths while passing visible light ** Chelsea filter, a dichromatic optical filter used for identifying coloured stones ** Astronomical filter, a telescope accessory used to enhance the details of celestial objects

Signal processing

Filter (signal processing) In signal processing, a filter is a device or process that removes some unwanted components or features from a Signal (electronics), signal. Filtering is a class of signal processing, the defining feature of filters being the complete or partial s ...

Electronic filter Electronic filters are a type of signal processing filter in the form of electrical circuits. This article covers those filters consisting of lumped-element model, lumped electronic components, as opposed to distributed-element filters. That ...

, an electronic circuit which processes signals, for example to remove unwanted frequency components **

Digital filter In signal processing, a digital filter is a system that performs mathematical operations on a Sampling (signal processing), sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other ma ...

, a system that performs mathematical operations to reduce or enhance certain aspects of a signal **

Analogue filter Analogue filters are a basic building block of signal processing much used in electronics. Amongst their many applications are the separation of an audio signal before application to bass, mid-range, and tweeter loudspeakers; the combining and ...

, a basic building block of signal processing much used in electronics ** Filters used in

digital image processing Digital image processing is the use of a digital computer to process digital images through an algorithm. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing. It allo ...

Arts and entertainment

* ''Filter'' (TV series), a show on the G4 channel * ''Filter'' (magazine), an indie music magazine *

Filter Theatre Filter Theatre is a British theatre company known for its groundbreaking use of sound and unconventional adaptions of classic texts. Claire Alfree of the Metro once called them "one of Britain's best and boldest devising companies". The company ...

, a British theatre company * The Filter, a digital content services company based in England *

Filter (band) Filter is an American rock music, rock band formed in 1993 in Cleveland, Ohio, by singer Richard Patrick, along with guitarist and programmer Brian Liesegang. The band was formed when Patrick desired to start his own band after leaving Nine Inc ...

, an American rock band * "Filter", a song from the album '' Bend'' by 8stops7 * "Filter", a song from the album '' Map of the Soul: 7'' by BTS * "Filter", a song from the album ''

Ruby Ruby is a pinkish-red-to-blood-red-colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapph ...

'' by Jennie

Other uses

Biofilter Biofiltration is a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, a ...

, a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants * Filtering (housing), the process of housing units becoming more affordable with age *

Category Category, plural categories, may refer to: General uses *Classification, the general act of allocating things to classes/categories Philosophy * Category of being * ''Categories'' (Aristotle) * Category (Kant) * Categories (Peirce) * Category ( ...

-based filtering of perception, according to (objectivist interpretations of) Kant **

Affective filter The input hypothesis, also known as the monitor model, is a group of five hypotheses of second-language acquisition developed by the linguist Stephen Krashen in the 1970s and 1980s. Krashen originally formulated the input hypothesis as just o ...

, an impediment to learning or acquisition caused by negative emotional ("affective") responses to one's environment *

Lane splitting Lane splitting is riding a bicycle or motorcycle between lanes or rows of slow moving or stopped traffic moving in the same direction. It is sometimes called whitelining, or stripe-riding. This allows riders to save time, bypassing traffic cong ...

, a practice that cyclists use to pass slow or stopped congested traffic *The ability of a person to

self-censor Self-censorship is the act of censoring or classifying one's own discourse, typically out of fear or deference to the perceived preferences, sensibilities, or infallibility of others, and often without overt external pressure. Self-censorship is co ...

themselves (their thoughts) whilst speaking