B or b (pronounced ) is the second letter of the ISO basic Latin alphabet. It represents the voiced bilabial stop in many languages, including English. In some other languages, it is used to represent other bilabial consonants.
Old English was originally written in runes, whose equivalent letter was beorc , meaning "birch". Beorc dates to at least the 2nd-century Elder Futhark, which is now thought to have derived from the Old Italic alphabets' either directly or via Latin alphabet .
The Uncial script and half-uncial introduced by the Gregorian and Irish missions gradually developed into the ' . These Old English Latin alphabets supplanted the earlier runes, whose use was fully banned under King Canute in the early 11th century. The Norman Conquest popularized the Carolingian half-uncial forms which latter developed into blackletter . Around 1300, letter case was increasingly distinguished, with capitalization and lower-case B taking separate meanings. Following the advent of printing in the 15th century, Germany and Scandinavia continued to use forms of blackletter (particularly Fraktur), while England eventually adopted the humanist and antiqua scripts developed in Renaissance Italy from a combination of Roman inscriptions and Carolingian texts. The present forms of the English cursive B were developed by the 17th century.
The Roman derived from the Greek alphabet capital beta via its Etruscan and Cumaean variants. The Greek letter was an adaptation of the Phoenician letter bēt . The Ancient Egypt hieroglyph for the consonant /b/ had been an image of a foot and calf , but bēt (Phoenician for "house") was a modified form of a Proto-Sinaitic glyph probably adapted from the separate hieroglyph Pr meaning "house".It also resembles the hieroglyph for /h/ meaning "manor" or "reed shelter". The Hebrew alphabet letter beth is a separate development of the Phoenician letter.
By Byzantine Greek, the Greek letter came to be pronounced /v/, so that it is known in modern Greek as víta (still written βήτα). The Cyrillic letter ve represents the same sound, so a modified form known as be was developed to represent the Slavic languages' /b/. (Modern Greek continues to lack a letter for the voiced bilabial plosive and transliterates such sounds from other languages using the digraph/consonant cluster , mp.)
As /b/ is one of the sounds subject to Grimm's Law, words which have in English and other Germanic languages may find their cognates in other Indo-European languages appearing with , , or instead. For example, compare the various cognates of the word .
In Estonian, Icelandic, and Chinese language Pinyin, does not denote a voiced consonant. Instead, it represents a voiceless that contrasts with either a (in Estonian) or an aspirated (in Pinyin, Danish and Icelandic) represented by . In Fijian language represents a prenasalized , whereas in Zulu language and Xhosa language it represents an implosive , in contrast to the digraph which represents . Finnish language uses only in loanwords.
In Contracted (grade 2) English braille, 'b' stands for "but" when in isolation.
In computer science, B is the symbol for byte, a unit of information storage.
In engineering, B is the symbol for decibel, a unit of level.