B (disambiguation)

B is the second letter of the English alphabet.

B or b may also refer to:

 Boron (B), an element
 Bit (bit or b), a unit of information
 Byte (B), eight bits
 Bel (B), ten decibels
 Bar (unit), a unit of pressure
 Barn (unit), a unit of area equal to the quectoare
 B, a musical note