Affinity
Affinity may refer to:

Commerce, finance and law
Affinity (law), kinship by marriage
Affinity analysis, a market research and business management technique
Affinity Credit Union, a Saskatchewan-based credit union
Affinity Equity Partners, an Asian private equity firm
Affinity fraud, a type of scam targeting a specific demographic
Affinity marketing, a method of extending market reach by forming partnerships and cross-selling relationships

Religion and belief
Affinity (canon law), a kinship arising from the sexual intercourse of a man and a woman
Affinity (Christian organisation), network of conservative evangelical churches and Christian agencies
Affinity group, a private, non-commercial and non-governmental organisation formed around a shared interest or goal

Science and technology
Affinity, the UK's first road-legal solar car, built by Cambridge University Eco Racing
Affinity (mathematics), an affine transformation preserving collinearity
Affinity (pharmacology), a characterisation of protein-ligand binding strength
Affinity (sociology), a shared interest and commitment between persons in groups and/or willingness to associate
Affinity (taxonomy), a suggestion of common descent or type
Affinity chromatography, method of separating a biomolecule from a mixture
Affinity electrophoresis, general name for many analytical methods used in biochemistry and biotechnology
Affinity laws, laws used in hydraulics to express relationships between variables involved in fan or pump performance
Binding affinity, a measure of the interaction of ligands with their binding sites
Chemical affinity, used to describe or characterise elements' or compounds' readiness to form bonds
Electron affinity, energy released on formation of anions
Processor affinity, a computing term for the assignment of a task to a given core of a multicore CPU
Serif Europe's Affinity series of programs
Affinity Designer, a vector illustration editor
Affinity Photo, a raster graphics editor
Affinity Publisher, a desktop publishing application

Media-related
Music
Affinity (band), a jazz/rock band
Affinity (Affinity album)
Affinity (Bill Evans album)
Affinity (Haken album)
Affinity (Oscar Peterson album)
Affinity (EP), a 2013 EP by the English band Press to Meco
Johnny Alegre A, a jazz collective based in Manila

Other media
Affinity (novel), a 1999 novel by Sarah Waters
Affinity (film), a 2008 feature film based on the novel
"Affinity" (Stargate SG-1), an episode from season 8 of the TV sci-fi spin-off series Stargate SG-1
Elective Affinities, a novel by Goethe

Other uses
Affinity (medieval), late medieval retainers of a monarch in "bastard feudalism"
Affinity, West Virginia

See also
Affine (disambiguation)
Affine transformation, a type of transformation applied to a geometry
Refining, also known as "affining"
Afinidad (disambiguation)