B, a letter grade

Blood type B

Magnetic Field, used to represent the density of a magnetic Field in Physics

Boron, the chemical element

Bel, a unit of ratio (virtually only used with the prefix deci: dB)

Buoyancy ("B"), in physics and atmopsheric sciences:

Baron, in judicial reports

Bishop (chess), chess piece

Convective available potential energy, positive buoyancy (B or B+)

Convective inhibition, negative buoyancy (B-)

B (programming language)

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

B, the abbreviation for the orchid genus Brassavola

B-Method, a formal method for software development

B Battery

B (musical note)

Haplogroup B (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup

Flat (music), the symbol for which highly resembles the lowercase letter "b"

Haplogroup B (Y-DNA), a Y-chromosomal DNA (Y-DNA) haplogroup

A • B • C • D • E • F • G • H • I • J • K • L • M • N • O • P • Q • R • S • T • U • V • W • X • Y • Z