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 (${\displaystyle \mathbb {B} }$), 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

Music

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