Number sign

#
Number sign
Punctuation
apostrophe  '
brackets [ ]  ( )  { }  ⟨ ⟩
colon :
comma ,  ،  
dash ‒  –  —  ―
ellipsis  ...      
exclamation mark !
full stop, period .
guillemets ‹ ›  « »
hyphen
hyphen-minus -
question mark ?
quotation marks ‘ ’  “ ”  ' '  " "
semicolon ;
slash, stroke, solidus /    
Word dividers
interpunct ·
space     
General typography
ampersand &
asterisk *
at sign @
backslash \
basis point
bullet
caret ^
dagger † ‡ ⹋
degree °
ditto mark
equals sign =
inverted exclamation mark ¡
inverted question mark ¿
komejirushi, kome, reference mark
number sign, pound, hash #
numero sign
obelus ÷
ordinal indicator º ª
percent, per mil % ‰
pilcrow
plus, minus + −
plus-minus, minus-plus ± ∓
prime    
section sign §
tilde ~
underscore, understrike _
vertical bar, pipe, broken bar |    ¦
Intellectual property
copyright ©
copyleft 🄯
sound-recording copyright
registered trademark ®
service mark
trademark
Currency
currency sign ¤

؋฿¢$֏ƒ£元 圆 圓 ¥

Uncommon typography
asterism
fleuron, hedera
index, fist
interrobang
irony punctuation
lozenge
tie
Related
In other scripts

The symbol # is most commonly known as the number sign,[1] hash,[2] or pound sign.[3] The symbol has historically been used for a wide range of purposes, including the designation of an ordinal number and as a ligatured abbreviation for pounds avoirdupois (having been derived from the now-rare ℔).[4]

Since 2007, widespread usage of the symbol to introduce metadata tags on social media platforms has led to such tags being known as "hashtags"[5] and from that, the symbol itself is sometimes called a "hashtag".[6]

The symbol is defined in Unicode and ASCII as U+0023 # NUMBER SIGN (HTML #) and # in HTML5.[7] It is graphically similar to several other symbols, including the sharp () from musical nomenclature and the equal-and-parallel symbol (⋕) from mathematics, but is distinguished by its combination of level horizontal strokes and right-tilting vertical strokes.

History

A stylized version of the abbreviation for libra pondo ("pound weight").
The abbreviation written by Isaac Newton, showing the evolution from ℔ toward #.

It is believed that the symbol traces its origins to the symbol ℔, an abbreviation of the Roman term libra pondo, which translates as "pound weight".[8][9] This abbreviation was printed with a dedicated ligature type, with a horizontal line across, so that the lowercase letter "l" would not be mistaken for the numeral "1". Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two slash-like strokes "//".[9] Examples of it being used to indicate pounds exist at least as far back as 1850.[10]

The symbol is described as the "number" character in an 1853 treatise on bookkeeping.[11] and its double meaning is described in a bookkeeping text from 1880.[12] The instruction manual of the Blickensderfer model 5 typewriter (c. 1896) appears to refer to the symbol as the "number mark".[13] Some early 20th-century U.S. sources refer to it as the "number sign",[14] although this could also refer to the numero sign.[15] A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)"; and "pounds (written after a figure)".[16]

The use of the phrase "pound sign" to refer to this symbol is found from 1932 in U.S. usage. Before this time, and still outside the United States, the term "pound sign" was used to refer to the pound currency symbol (£) or the pound weight symbol (lb).[17] An alternative theory is that the name "pound sign" arose from the fact that character encodings used the same code for both the number sign and the British pound sign "£". Claims have included ISO 646-GB as well as the Baudot code in the late 19th century.[18] The apparent use of the sign to mean pounds weight in 1850 appears to rule out both of these code sets as the origin, although that same reference admits that the earliest reference in print was a decade after Baudot code.[10]

"Hash sign" is found in South African writings from the late 1960s,[19] and from other non-North-American sources in the 1970s.[citation needed]

The symbol appears to be used primarily in handwritten material, while in the printing business, the numero (№) symbol and barred-lb (℔) are used for "number" and "pounds" respectively.

For mechanical devices, it appeared on the keyboard of the Remington Standard typewriter (c. 1886),[20] but was not used on the keyboards used for typesetting.[10] It appeared in many of the early teleprinter codes and from there was copied to ASCII which made it available on computers and thus caused many more uses to be found for the character. The symbol was introduced on the bottom right button of touch-tone keypads in 1968, but that button was not extensively used until the advent of large scale voicemail (PBX systems, etc.) in the early 1980s.[21]

Other Languages
العربية: رمز الرقم
azərbaycanca: Diyez işarəsi
català: Quadradet
čeština: Křížek (znak)
dansk: Nummertegn
español: Almohadilla
한국어: 해시 기호
հայերեն: Վանդականիշ
íslenska: Tvíkross
italiano: Cancelletto
עברית: סולמית
lietuvių: Grotelės
magyar: Számjel
Nederlands: Hekje
日本語: 番号記号
norsk: Nummertegn
português: Cerquilha
русский: Знак решётки
slovenščina: Številski znak
svenska: Nummertecken
Türkçe: Kare işareti
українська: Знак решітки
粵語: 井號
中文: 井號