Editing CAS Registry Number (section)

== History and use ==
Historically, chemicals have been identified by a wide variety of synonyms and propeties. One of the biggest challenges in the early development of substance indexing, a task undertaken by the Chemical Abstracts Service, was in identifying if a substance in literature was new or if it had been previously discovered. Well-known chemicals may be known via multiple generic, historical, commercial, and/or [[Black market|(black)-market]] names, and even [[Chemical nomenclature|systematic nomenclature]] based on structure alone was not universally useful. An algorithm was developed to translate the [[structural formula]] of a chemical into a computer-searchable table, which provided a basis for the service that listed each chemical with its CAS Registry Number, the CAS Chemical Registry System, which became operational in 1965.<ref>{{Cite web |last=Shively |first=Eric |date=June 11, 2007 |title=CAS Surveys Its First 100 Years |url=https://cen.acs.org/articles/85/i24/CAS-Surveys-First-100-Years.html |access-date=2024-04-16 |website=Chemical & Engineering News |language=en}}</ref>

CAS Registry Numbers (CAS RN) are simple and regular, convenient for database searches. They offer a reliable, common and international link to every specific substance across the various nomenclatures and disciplines used by branches of science, industry, and regulatory bodies. Almost all molecule databases today allow searching by CAS Registry Number, and it is used as a global standard.<ref>{{Cite journal |last=Jacobs |first=Andrea |last2=Williams |first2=Dustin |last3=Hickey |first3=Katherine |last4=Patrick |first4=Nathan |last5=Williams |first5=Antony J. |last6=Chalk |first6=Stuart |last7=McEwen |first7=Leah |last8=Willighagen |first8=Egon |last9=Walker |first9=Martin |last10=Bolton |first10=Evan |last11=Sinclair |first11=Gabriel |last12=Sanford |first12=Adam |date=2022-06-13 |title=CAS Common Chemistry in 2021: Expanding Access to Trusted Chemical Information for the Scientific Community |url=https://pubs.acs.org/doi/10.1021/acs.jcim.2c00268 |journal=Journal of Chemical Information and Modeling |language=en |volume=62 |issue=11 |pages=2737–2743 |doi=10.1021/acs.jcim.2c00268 |issn=1549-9596 |pmc=9199008 |pmid=35559614}}</ref>