#
Number sign
In UnicodeU+0023 # NUMBER SIGN (#)
Different from
Different fromU+266F MUSIC SHARP SIGN
U+2317 VIEWDATA SQUARE
U+22D5 EQUAL AND PARALLEL TO
Related
See alsoU+00A3 £ POUND SIGN
U+2116 NUMERO SIGN

The symbol # is known variously in English-speaking regions 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 distinguished from similar symbols 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 ,[a] an abbreviation of the Roman term libra pondo, which translates as "pound weight".[7][8] This abbreviation was printed with a dedicated ligature type element, 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 "//".[8]

The symbol is described as the "number" character in an 1853 treatise on bookkeeping,[9] and its double meaning is described in a bookkeeping text from 1880.[10] The instruction manual of the Blickensderfer model 5 typewriter (c. 1896) appears to refer to the symbol as the "number mark".[11] Some early-20th-century U.S. sources refer to it as the "number sign",[12] although this could also refer to the numero sign.[13] A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)" and "pounds (written after a figure)".[14] The use of the phrase "pound sign" to refer to this symbol is found from 1932 in U.S. usage.[15] The term hash sign is found in South African writings from the late 1960s[16] and from other non-North-American sources in the 1970s.[citation needed]

The symbol appears to have been used primarily in handwritten material; in the printing business, the numero symbol (№) and barred-lb (℔) were used for "number" and "pounds" respectively.[where?][citation needed]

For mechanical devices, the symbol appeared on the keyboard of the Remington Standard typewriter (c. 1886).[17] 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.[4]

One of the uses in computers was to label the following text as having a different interpretation (such as a command or a comment) from the rest of the text. It was adopted for use within internet relay chat (IRC) networks circa 1988 to label groups and topics.[18] This usage inspired Chris Messina to propose a similar system to be used on Twitter to tag topics of interest on the microblogging network;[19][20] this became known as a hashtag. Although used initially and most popularly on Twitter, hashtag use has extended to other social media sites.[21]

Names

Number sign

'Number sign' is the name chosen by the Unicode consortium. Most common in Canada[22] and the northeastern United States.[citation needed] American telephone equipment companies which serve Canadian callers often have an option in their programming to denote Canadian English, which in turn instructs the system to say number sign to callers instead of pound.[23]

Pound sign or pound

'Pound sign' or 'pound' are the most common names used in the United States, where the '#' key on a phone is commonly referred to as the pound key or simply pound. Dialing instructions to an extension such as #77, for example, can be read as "pound seven seven".[24] This name is rarely used outside the United States, where the term pound sign is understood to mean the currency symbol £.

Hash, hash mark, hashmark

In the United Kingdom,[25] Australia,[26] and some other countries,[citation needed] it is generally called a 'hash' (probably from 'hatch', referring to cross-hatching[27]).
Programmers also use this term; for instance #! is "hash, bang" or "shebang".

Hashtag

Derived from the previous, the word 'hashtag' is often used when reading social media messages aloud, indicating the start of a hashtag. For instance, the text "#foo" is often read out loud as "hashtag foo" (as opposed to "hash foo"). This leads to the common belief that the symbol itself is called hashtag.[6] Twitter documentation refers to it as "the hashtag symbol".[28]

Hex

'Hex' is commonly used in Singapore and Malaysia, as spoken by many recorded telephone directory-assistance menus: "Please enter your phone number followed by the 'hex' key". The term 'hex' is discouraged in Singapore in favour of 'hash'. In Singapore, a hash is also called 'hex' in apartment addresses, where it precedes the floor number.[29][30]

Octothorp, octothorpe, octathorp, octatherp

Most scholars believe the word was invented by workers at the Bell Telephone Laboratories by 1968,[31] who needed a word for the symbol on the telephone keypad. Don MacPherson is said to have created the word by combining octo and the last name of Jim Thorpe, an Olympic medalist.[32] Howard Eby and Lauren Asplund claim to have invented the word as a joke in 1964, combining octo with the syllable therp which, because of the "th" digraph, was hard to pronounce in different languages.[33] The Merriam-Webster New Book of Word Histories, 1991, has a long article that is consistent with Doug Kerr's essay,[33] which says "octotherp" was the original spelling, and that the word arose in the 1960s among telephone engineers as a joke. Other hypotheses for the origin of the word include the last name of James Oglethorpe[34] or using the Old English word for village, thorp, because the symbol looks like a village surrounded by eight fields.[35][36] The word was popularized within and outside Bell Labs.[37] The first appearance of "octothorp" in a US patent is in a 1973 filing. This patent also refers to the six-pointed asterisk (✻) used on telephone buttons as a "sextile".[38]

Sharp

Use of the name 'sharp' is due to the symbol's resemblance to U+266F MUSIC SHARP SIGN. The same derivation is seen in the name of the Microsoft programming languages C#, J# and F#. Microsoft says, "It's not the 'hash' (or pound) symbol as most people believe. It's actually supposed to be the musical sharp symbol. However, because the sharp symbol is not present on the standard keyboard, it's easier to type the hash symbol (#). The name of the language is, of course, pronounced 'see sharp'."[39] According to the ECMA-334 C# Language Specification, section 6, Acronyms and abbreviations, the name of the language is written "C#" ("LATIN CAPITAL LETTER C (U+0043) followed by the NUMBER SIGN # (U+0023)") and pronounced "C Sharp".[40]

Square

Detail of a telephone keypad displaying the Viewdata square
On telephones, the International Telecommunication Union specification ITU-T E.161 3.2.2 states: "The symbol may be referred to as the square or the most commonly used equivalent term in other languages."[41] Formally, this is not a number sign but rather another character, U+2317 VIEWDATA SQUARE. The real or virtual keypads on almost all modern telephones use the simple # instead, as does most documentation.[citation needed].

Other

Names that may be seen include:[4][42][better source needed] crosshatch, crunch, fence, flash, garden fence, garden gate, gate, grid, hak, mesh, oof, pig-pen, punch mark, rake, scratch, scratch mark, tic-tac-toe, and unequal.

Usage

When ⟨#⟩ prefixes a number, it is read as "number". "A #2 pencil", for example, indicates "a number-two pencil". The abbreviations 'No.' and '№' are used commonly and interchangeably. The use of ⟨#⟩ as an abbreviation for "number" is common in informal writing, but use in print is rare.[43] Where Americans might write "Symphony #5", British and Irish people usually write "Symphony No. 5".

When ⟨#⟩ is after a number, it is read as "pound" or "pounds", meaning the unit of weight. The text "5# bag of flour" would mean "five-pound bag of flour". The abbreviations "lb." and "℔" are used commonly and interchangeably. This usage is rare outside North America, where 'lb' or 'lbs' is used.

⟨#⟩ is not a replacement for the pound sign ⟨£⟩, but British typewriters and keyboards have a £ key where American keyboards have a # key.[44] Many early computer and teleprinter codes (such as BS 4730 (the UK national variant of the ISO/IEC 646 character set) substituted '£' for '#' to make the British versions, thus it was common for the same binary code to display as # on US equipment and £ on British equipment ('$' was not substituted to avoid confusing dollars and pounds in financial communications).

Mathematics

Computing

Other uses

Unicode

In Unicode, several # characters are assigned. Other attested names in Unicode are: pound sign, hash, crosshatch, octothorpe.


Character information
Preview #
Unicode name NUMBER SIGN FULLWIDTH NUMBER SIGN SMALL NUMBER SIGN
Encodings decimal hex dec hex dec hex
Unicode 35 U+0023 65283 U+FF03 65119 U+FE5F
UTF-8 35 23 239 188 131 EF BC 83 239 185 159 EF B9 9F
GB 18030 35 23 163 163 A3 A3 169 124 A9 7C
Numeric character reference # # # # ﹟ ﹟
Named character reference #
ASCII and extensions 35 23
EBCDIC (037, 500, UTF)[61][62][63] 123 7B
EBCDIC (1026)[64] 236 EC
Shift JIS[65] 35 23 129 148 81 94
EUC-JP[66] 35 23 161 244 A1 F4
EUC-KR[67] / UHC[68] 35 23 163 163 A3 A3
Big5[69] 35 23 161 173 A1 AD 161 204 A1 CC
EUC-TW 35 23 161 236 A1 EC 162 173 A2 AD
LaTeX[70] \#


Character information
Preview #️⃣
Unicode name KEYCAP NUMBER SIGN[71]
Encodings decimal hex
Unicode 35 65039 8419 U+0023+FE0F+20E3
UTF-8 35 239 184 143 226 131 163 23 EF B8 8F E2 83 A3
GB 18030 35 132 49 130 53 129 54 184 54 23 84 31 82 35 81 36 B8 36
Numeric character reference #️⃣ #️⃣
Shift JIS (NTT Docomo)[72] 249 133 F9 85
Shift JIS (SoftBank 3G)[73] 247 176 F7 B0
Shift JIS (au by KDDI)[74] 244 137 F4 89
7-bit JIS (au by KDDI and others)[75] 123 105 7B 69
Emoji shortcode[76] :hash:

At least three orthographically distinct number signs from other languages are also assigned:

On keyboards

On the standard US keyboard layout, the # symbol is ⇧ Shift+3. On standard UK and some other European keyboards, the same keystrokes produce the pound (sterling) sign, £ symbol, and # may be moved to a separate key above the right shift key. If there is no key, the symbol can be produced on Windows with Alt+35, on Mac OS with ⌥ Opt+3, and on Linux with Compose++.

See also

Explanatory notes

  1. ^ U+2114 L B BAR SYMBOL

References

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