Editing Number sign (section)

==History==
[[File:Pfund.svg|thumb|A stylized version of the abbreviation for ''[[Roman pound|libra pondo]]'' ("pound weight")|upright]]
[[File:Libra pondo abbreviation newton.jpg|thumb|The abbreviation written by [[Isaac Newton]], showing the evolution from "{{not a typo|℔}}" toward "#"]]
It is believed that the symbol traces its origins to the symbol {{char|℔}},{{efn|{{unichar|2114|html=|nlink=}} }} an abbreviation of the Roman term ''[[Roman pound|libra pondo]]'', which translates as "pound weight".<ref>{{cite book | quote=The Italian ''libbra'' (from the old Latin word ''libra'', 'balance') represented a weight almost exactly equal to the [[avoirdupois]] pound of England. The Italian abbreviation of lb with a line drawn across the letters was used for both weights. | author =Keith Gordon Irwin | title= The romance of writing, from Egyptian hieroglyphics to modern letters, numbers, and signs | page= 125 | location= New York |publisher= Viking Press | year = 1967 | orig-year = 1956}}</ref><ref name="NewYorker" /> The abbreviation "lb" was printed as a dedicated [[Ligature (writing)|ligature]] including a horizontal line across (which indicated abbreviation).<ref>{{cite web | url= http://www.royalmintmuseum.org.uk/Default.aspx?PageID=14314417 | title=The Origins of £sd | publisher=The Royal Mint Museum |archive-url = https://web.archive.org/web/20200308111135/http://www.royalmintmuseum.org.uk/Default.aspx?PageID=14314417 |archive-date= 8 March 2020 |quote=It is not known for certain when the horizontal line or lines, which indicate an abbreviation, first came to be drawn through the L.}}</ref><ref name="NewYorker" /> Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two slash-like strokes "//".<ref name="NewYorker">{{cite news|last=Houston|first=Keith|title=The Ancient Roots of Punctuation|url=http://www.newyorker.com/online/blogs/books/2013/09/origins-of-hashtag-manicule-diple-pilcrow-ampersand-explained.html|access-date=16 October 2013|newspaper=The New Yorker|date=2013-09-06|archive-date=2014-06-25|archive-url=https://web.archive.org/web/20140625175614/http://www.newyorker.com/online/blogs/books/2013/09/origins-of-hashtag-manicule-diple-pilcrow-ampersand-explained.html|url-status=live}}</ref> 

The symbol is described as the "number" character in an 1853 treatise on [[bookkeeping]],<ref>{{cite book|last1=Crittendon|first1=S. W.|title=An Elementary Treatise on Book-keeping by Single and Double Entry |date=1853 |publisher=E., C., & J. Biddle |location=Philadelphia |page=10 |url=https://archive.org/details/anelementarytre00critgoog/page/n16/mode/1up |access-date=7 February 2023}}</ref> and its double meaning is described in a bookkeeping text from 1880.<ref>{{cite book|last1=Duff|first1=C. P.|last2=Duff|first2=W. H.|last3=Duff|first3=R. P.|title=Book-Keeping By Single and Double Entry|date=1880|publisher=Harper and Brothers|page=[https://archive.org/details/bookkeepingbysi00duffgoog/page/n27 21]|url=https://archive.org/details/bookkeepingbysi00duffgoog|access-date= 24 November 2015}}</ref> The instruction manual of the [[Blickensderfer typewriter#Model 5|Blickensderfer model 5]] typewriter ({{Circa|1896}}) appears to refer to the symbol as the "number mark".<ref>{{cite book |author= |url=http://site.xavier.edu/polt/typewriters/Blick5manual.pdf |title=Method of Operating and Instructions for Practice on the Blickensderfer Typewriter |publisher=K. M. Turner |year=1896 |location=Atlanta, GA |page=14 |quote=It is best to use the 'number mark' for plus; the hyphen for minus, and two hyphens for the sign = |archive-url=https://web.archive.org/web/20211014223637/https://site.xavier.edu/polt/typewriters/Blick5manual.pdf |archive-date=Oct 14, 2021}}</ref> Some early-20th-century U.S. sources refer to it as the "number sign",<ref>e.g. J. W. Marley, "The Detection and Illustration of Forgery By Comparison of Handwriting", in {{cite book |url=https://books.google.com/books?id=Z_NEAQAAMAAJ&pg=PA180 |title=Proceedings of the Sixteenth Annual Convention of the Kansas Bankers' Association |publisher=Rusell |year=1903 |location=Kansas City |page=180}}</ref> although this could also refer to the [[numero sign]]  ({{not a typo|№}}).<ref>e.g. [https://books.google.com/books?id=CPodAQAAIAAJ&pg=RA2-PA395 ''The British Printer'' vol. viii] (1895), p. 395</ref> A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)" and "pounds (written after a figure)".<ref>{{cite book |title=Business Arithmetic for Secondary Schools |first=Ernest L. |last=Thurston |location=New York |publisher=Macmillan |year=1917 |page=[https://archive.org/details/businessarithme02thurgoog/page/n439 419] |url=https://archive.org/details/businessarithme02thurgoog|quote=business symbols pound. }}</ref> The use of the phrase "pound sign" to refer to this symbol is found from 1932 in U.S. usage.<ref>{{cite book |first=Nancy M. |last=Lawrence |author2=F. Ethel McAfee |author3=Mildred M. Butler |title=Correlated studies in stenography |publisher=Gregg |year=1932 |page=141 |url=https://books.google.com/books?id=oCsOAQAAIAAJ}}</ref> The term ''hash sign'' is found in South African writings from the late 1960s<ref>''Research Review. Navorsingsoorsig'' vols. 18–21, pp. 117, 259 (1968)</ref> and from other non-North-American sources in the 1970s.{{citation needed|date=November 2017}}

For mechanical devices, the symbol appeared on the keyboard of the [[E. Remington and Sons|Remington]] Standard typewriter ({{Circa|1886}}).<ref>{{cite web|url=http://pds.lib.harvard.edu/pds/view/2574435?n=52&s=4&printThumbnails=no|title=Remington Standard typewriter |location=New York |publisher=Wyckoff, Seamans & Benedict |date=1886 |page=50}}</ref> 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 [[Push-button telephone|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.<ref name="Houston" />

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 ([[Internet Relay Chat|IRC]]) networks circa 1988 to label groups and topics.<ref>"Channel Scope". Section 2.2. {{IETF RFC|2811}}</ref> This usage inspired [[Chris Messina (open source advocate)|Chris Messina]] to propose a similar system to be used on [[Twitter]] to tag topics of interest on the microblogging network;<ref>{{cite web|url=http://www.cmu.edu/homepage/computing/2014/summer/originstory.shtml|title=#OriginStory|publisher=Carnegie Mellon University|date=August 29, 2014|access-date=August 23, 2019|archive-date=June 1, 2019|archive-url=https://web.archive.org/web/20190601233044/https://www.cmu.edu/homepage/computing/2014/summer/originstory.shtml|url-status=live}}</ref><ref>{{cite news |author=Parker, Ashley |date=June 10, 2011 |title=Twitter's Secret Handshake |work=The New York Times |url=https://www.nytimes.com/2011/06/12/fashion/hashtags-a-new-way-for-tweets-cultural-studies.html?_r=1&pagewanted=all |url-status=live |url-access=limited |access-date=July 26, 2011 |archive-url=https://web.archive.org/web/20110617001914/https://www.nytimes.com/2011/06/12/fashion/hashtags-a-new-way-for-tweets-cultural-studies.html?_r=1&pagewanted=all |archive-date=Jun 17, 2011}}</ref> this became known as a [[hashtag]]. Although used initially and most popularly on Twitter, hashtag use has extended to other social media sites.<ref>{{cite news |last=Warren |first=Christina |title=Facebook finally gets #hashtags |website=CNN |url=http://www.cnn.com/2013/06/12/tech/social-media/facebook-hashtags/index.html |url-status=live |access-date=July 16, 2006 |archive-url=https://web.archive.org/web/20130613102217/https://www.cnn.com/2013/06/12/tech/social-media/facebook-hashtags/index.html |archive-date=Jun 13, 2013}}</ref>
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