Duality
Duality may refer to:

Mathematics
Duality (mathematics), a mathematical concept
Dual (category theory), a formalization of mathematical duality
Duality (optimization)
Duality (order theory), a concept regarding binary relations
Duality (projective geometry), general principle of projective geometry
Duality principle (Boolean algebra), the extension of order-theoretic duality to Boolean algebras
S-duality (homotopy theory)
List of dualities § Mathematics

Philosophy, logic, and psychology
Dualistic cosmology, a twofold division in several spiritual and religious worldviews
Dualism (philosophy of mind), where the body and mind are considered to be irreducibly distinct
De Morgan's laws, specifically the ability to generate the dual of any logical expression
Complementary duality of Carl Jung's functions and types in Socionics

Science
Electrical and mechanical
Duality (electrical circuits), regarding isomorphism of electrical circuits
Duality (mechanical engineering), regarding isomorphism of some mechanical laws

Physics
AdS/CFT correspondence (anti de Sitter/conformal field theory correspondence), sometimes called the Maldacena duality
Dual resonance model
Duality (electricity and magnetism)
Englert–Greenberger duality relation
Holographic duality
Kramers–Wannier duality
List of dualities § Science: Physics
Mirror symmetry (string theory)
Montonen–Olive duality
Mysterious duality
String duality,  a class of symmetries
S-duality
T-duality
U-duality
Wave–particle duality

Music
Albums
Duality (Peter Leitch and John Hicks album), 1994
Duality (Lisa Gerrard and Pieter Bourke album), 1998
Duality (Set It Off album), 2014
Duality (Ra album), 2005
Duality (mixtape), 2012
Duality (Luna Li album), 2022
Duality, a 2009 album by Darker Half
Duality, a 2020 album by Duke Dumont
Duality, a 2018 album by Big Scoob

Songs
"Duality", a 2014 single from pop rock/punk rock band Set It Off
"Duality" (song), a 2004 single & Grammy-nominated song by metal band Slipknot
"Duality", a 2007 single from alternative rock/punk band Bayside

Other
Duality (film), a 2001 Star Wars fan film by Dave Macomber and Mark Thomas
Duality, a large format audio mixing console by Solid State Logic
Duality (CoPs), refers to the notion of a duality in a Community of Practice
Dual (grammatical number), grammatical number that some languages use in addition to singular and plural

See also
Double (disambiguation)
Dual (disambiguation)
Duality principle (disambiguation)
List of dualities: philosophy, mathematics, physics and engineering
Nondualism (philosophy)
Triality (mathematics)