# B (disambiguation)

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), a human mitochondrial DNA (mtDNA) haplogroup
* Haplogroup B (Y-DNA), 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, 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)
* <b></b>, an 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)
* 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
* bottom quark (symbol: b), an elementary particle
* B meson, a type of meson
* Boolean domain ($\mathbb {B}$), 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 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), an extended play by BamBam
* B (Battles EP), an extended play by Battles
* B (I Am Kloot album), a compilation album by I Am Kloot
* 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

### Other media

* /b/, a board on 4chan
* 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

## 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
* The West Japan Railway Company service symbol for:
** Kosei Line
** Inbi Line
** Kabe Line
* Bundesstraße (federal highway) in Austria and Germany (abbreviation B)
* Bayshore Route of Shuto Expressway in Japan, numbered as route B
* Mexico City Metro Line B

## Other uses

* B (grade), for evaluation of students' work
* B (bank), a banking brand in the United Kingdom
* Barnabites (Latin: Clerici Regulares Sancti Pauli), a religious order abbreviated to the postnominal 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
* B, a soft grade of pencil lead