Editing MacOS (section)

=== Development ===
{{Main|macOS version history}}
The heritage of what would become macOS had originated at [[NeXT]], a company founded by [[Steve Jobs]] following his departure from Apple in 1985. There, the [[Unix-like]] [[NeXTSTEP]] operating system was developed, before being launched in 1989. The [[kernel (operating system)|kernel]] of NeXTSTEP is based upon the [[Mach (kernel)|Mach kernel]], which was originally developed at [[Carnegie Mellon University]], with additional kernel layers and low-level [[user space]] code derived from parts of [[FreeBSD]]<ref name="apple_bsd_overview">{{Cite web |year=2002 |title=Apple BSD Overview |url=https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/BSD/BSD.html |access-date=January 1, 2002 |publisher=Apple |archive-date=November 7, 2018 |archive-url=https://web.archive.org/web/20181107021823/https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/KernelProgramming/BSD/BSD.html |url-status=live }}</ref> and other [[BSD]] operating systems.<ref>{{Cite book |title=NeXTstep Concepts |publisher=[[NeXT]] |chapter=1. System Overview |chapter-url=https://www.nextcomputers.org/NeXTfiles/Docs/NeXTStep/3.3/nd/Concepts/Pre3.0_Concepts/01_SysOver.htmld/index.html |access-date=March 26, 2021 |archive-date=November 21, 2021 |archive-url=https://web.archive.org/web/20211121155935/https://www.nextcomputers.org/NeXTfiles/Docs/NeXTStep/3.3/nd/Concepts/Pre3.0_Concepts/01_SysOver.htmld/index.html |url-status=live }}</ref> Its [[graphical user interface]] was built on top of an [[object-oriented]] [[GUI toolkit]] using the {{nowrap|[[Objective-C]]}} programming language.

Throughout the 1990s, Apple had tried to create a "next-generation" OS to succeed its [[classic Mac OS]] through the [[Taligent]], [[Copland (operating system)|Copland]] and [[Gershwin operating system|Gershwin]] projects, but all were eventually abandoned.<ref>{{Cite web |title=Apple Facts |url=https://www.theapplemuseum.com/index.php?id=44 |url-status=live |archive-url=https://web.archive.org/web/20081221134115/https://www.theapplemuseum.com/index.php?id=44 |archive-date=December 21, 2008 |access-date=December 15, 2008 |publisher=The Apple Museum |quote=a joint venture with IBM, called Taligent, but was discontinued soon thereafter |df=mdy-all}}</ref> This led Apple to acquire [[NeXT]] in 1997, allowing NeXTSTEP, later called [[OpenStep|OPENSTEP]], to serve as the basis for Apple's next generation operating system.<ref>{{Cite news |last=Markoff |first=John |date=December 23, 1996 |title=Why Apple Sees Next as a Match Made in Heaven |page=D1 |work=[[The New York Times]] |url=https://query.nytimes.com/gst/fullpage.html?res=9F06E1D71331F930A15751C1A960958260 |url-status=live |archive-url=https://web.archive.org/web/20080531063010/https://query.nytimes.com/gst/fullpage.html?res=9F06E1D71331F930A15751C1A960958260 |archive-date=May 31, 2008 |df=mdy-all}}</ref>
This purchase also led to Steve Jobs returning to Apple as an interim, and then the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals. The project was first codenamed "[[Rhapsody (operating system)|Rhapsody]]" before officially being named Mac OS X.<ref>{{Cite web |last=Fawcett |first=Neil |date=February 12, 1998 |title=Rhapsody suffers an identity crisis |url=https://business.highbeam.com/411267/article-1G1-20334085/rhapsody-suffers-identity-crisis |url-status=dead |archive-url=https://web.archive.org/web/20130502033350/https://business.highbeam.com/411267/article-1G1-20334085/rhapsody-suffers-identity-crisis |archive-date=May 2, 2013 |access-date=April 19, 2012 |website=[[Computer Weekly]] |publisher=[[Reed Business Information]] |df=mdy-all}}{{subscription required}}</ref><ref name="Rhapsody and Blues">{{Cite web |last=Siracusa |first=John |date=April 3, 2008 |title=Rhapsody and Blues |url=https://arstechnica.com/staff/2008/04/rhapsody-and-blues |url-status=live |archive-url=https://web.archive.org/web/20151104224017/https://arstechnica.com/staff/2008/04/rhapsody-and-blues |archive-date=November 4, 2015 |access-date=30 November 2015 |website=[[Ars Technica]] |df=mdy-all}}</ref>