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 computer program to process a data stream * Filter (video), a software component that performs some operation on a multimedia stream * Information filtering system ** Email filtering, the processing of email to organize it according to specified criteria * Content-control software 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, 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), 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), 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, 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 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, removes impurities from water by means of a fine physical barrier, a chemical process or a biological process ** Cigarette filter, a part of a cigarette intended to filter the smoke inhaled by a smoker ** Coffee filter, 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) * Sieve 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), 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), a mathematical model for a number of filtering problems in signal processing and the like. * Filtration (mathematics), an indexed set of subobjects of a given algebraic structure S.

Optics

* Optical filter, selectively transmits light of different wavelengths ** Interference filter, 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, 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, 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, a basic building block of signal processing much used in electronics ** Filters used in digital image processing

Arts and entertainment

* ''Filter'' (TV series), a show on the G4 channel * ''Filter'' (magazine), an indie music magazine * Filter Theatre, 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, an impediment to learning or acquisition caused by negative emotional ("affective") responses to one's environment * Lane splitting, a practice that cyclists use to pass slow or stopped congested traffic *The ability of a person to self-censor themselves (their thoughts) whilst speaking