B is the second letter of the Latin alphabet. B may also refer to:

Science, technology, and mathematics

Astronomy

* Astronomical objects in the Barnard list of dark nebulae (abbreviation B) * Latitude (''b'') in the galactic coordinate system

Biology and medicine

Haplogroup B (mtDNA) In human mitochondrial genetics, haplogroup B is a human mitochondrial DNA (mtDNA) haplogroup. Origin Haplogroup B is believed to have arisen in Asia some 50,000 years before present. Its ancestral haplogroup was haplogroup R. The greatest vari ...

, a human mitochondrial DNA (mtDNA) haplogroup *

Haplogroup B (Y-DNA) Haplogroup B (M60) is a human Y-chromosome DNA haplogroup common to paternal lineages in Africa. It is a primary branch of the haplogroup BT. B (M60) is common in parts of Africa, especially the tropical forests of West-Central Africa. It was ...

, a Y-chromosomal DNA (Y-DNA) haplogroup * Blood type B * ATC code B ''Blood and blood forming organs'', a section of the Anatomical Therapeutic Chemical Classification System * Vitamin B * Hepatitis B *

Berlin Botanical Garden and Botanical Museum The Berlin Botanic Garden and Botanical Museum (german: Botanischer Garten und Botanisches Museum Berlin) is a botanical garden in the locality of the borough of , Berlin, Germany. Constructed between 1897 and 1910 under the guidance of archi ...

, assigned the abbreviation B as a repository of herbarium specimens

Computing

* B (programming language) * B-Method, for computer software development * B-tree, a data structure * Bit (b) * Byte (B) * , an HTML element#b, HTML element denoting bold text

Physical and chemical quantities and units

* One of the reciprocal lattice vectors (''b*'') * Breadth (''b''); see length * Impact parameter (''b'') * Molality (''b'') * Barn (unit) (b), a unit of area * Magnetic field (''B'') * Napierian absorbance (''B'') * rigid rotor, Rotational constant (''B'') * Second virial coefficient (''B'') * Susceptance (''B'') * Bel (''B''), a logarithmic unit equal to ten decibels

Other uses in science, technology, and mathematics

* ''B'', a modal logic * Boolean domain (

\mathbb

), in mathematics * Boron, symbol B, a chemical element * Bulb (photography), a shutter-speed setting * B battery, a battery used to provide the plate voltage of a Battery (vacuum tube)#B battery, vacuum tube * B horizon, a layer of soil commonly known as subsoil * B, B+ and B−, expressions of buoyancy in convective available potential energy

Linguistics

* В, a letter of the Cyrillic alphabet * Voiced bilabial stop (b, in the International Phonetic Alphabet)

Arts and media

Music

Musical notation

* B (musical note) * B major, a scale * B minor, a scale * B major chord, Chord names and symbols (popular music) * Flat (music), a note lower in pitch by a semitone

Performers

* Beyoncé * B, member of Superorganism (band)

Recordings

* B (BamBam EP), ''B'' (BamBam EP), an extended play by BamBam * B (Battles EP), ''B'' (Battles EP), an extended play by Battles * B (I Am Kloot album), ''B'' (I Am Kloot album), a compilation album by I Am Kloot * b (Moxy Früvous EP), ''b'' (Moxy Früvous EP), an extended play by Moxy Früvous * "b", an Iamamiwhoami song * "B", a song by Todrick Hall from his 2018 album ''Forbidden (Todrick Hall album), Forbidden''

Other media

* /b/, a board on 4chan * the Baltimore Sun, ''b'' (newspaper), a free daily, tabloid sized newspaper, published by ''The Baltimore Sun'' * ''Codex Vaticanus Graecus 1209'', an ancient bible * Rajawali Televisi, previously named B Channel, a television channel in Indonesia * B, the production code for the 1963–64 ''Doctor Who'' serial ''The Daleks'' * B, a character in ''Total Drama: Revenge of the Island'' * ''"B" Is for Burglar'', the second novel in Sue Grafton's "Alphabet mystery" series, published in 1985

Places

* Belgium, on the vehicle registration plates of the European Union * Bucharest, on the Vehicle registration plates of Romania#County codes, vehicle registration plates of Romania

Sport

* Australian rules football positions#Full back, in Australian Rules football * B, often used after the name of football clubs to denote a reserve team

Transportation

* B (New York City Subway service) * B Line (Los Angeles Metro) * Line B (Buenos Aires Metro) * B (S-train), in Copenhagen * RER B, a line in the RER of Paris *Bundesstraße (federal highway) in Austria and Germany (abbreviation B) * Bayshore Route of Shuto Expressway in Japan, numbered as route B

Other uses

* B (grade), for evaluation of students' work * B (bank), a banking brand in the United Kingdom * Barnabites ( la, Clerici Regulares Sancti Pauli), a religious order abbreviated to the postnominal ''B.'' * List of military time zones#B, Bravo, the military time zone code for UTC+02:00 * Brutus, a Roman cognomen (abbreviation B) * Farmall B, a tractor produced by International Harvester from 1939 to 1947 * Dominical letter B for a common year starting on Saturday