Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing it for sluggish performance.
Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as 'dog-slow, feature poor' and Aqua as 'unbearably slow and a huge resource hog'.
The first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving later that year.
After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion.
The kernel of Ne XTSTEP is based upon the Mach kernel, which was originally developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD.
Consumer releases of Mac OS X included more backward compatibility.The "X" in Mac OS X and OS X is the Roman numeral for the number 10 and is pronounced as such.The X was a prominent part of the operating system's brand identity and marketing in its early years, but gradually receded in prominence since the release of Snow Leopard in 2009.Version 10.4, Tiger, reportedly shocked executives at Microsoft by offering a number of features, such as fast file searching and improved graphics processing, that Microsoft had spent several years struggling to add to Windows with acceptable performance.Targeting the consumer and media markets, Apple emphasized its new "digital lifestyle" applications such as the i Life suite, integrated home entertainment through the Front Row media center and the Safari web browser.Previous Macintosh operating systems (versions of the classic Mac OS) were named using Arabic numerals, as with Mac OS 8 and Mac OS 9.The letter "X" in Mac OS X's name refers to the number 10, a Roman numeral.The latest version is mac OS High Sierra, which was publicly released in September 2017.Between 19, Apple sold a separate series of operating systems called Mac OS X Server.The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5.After this, new versions were introduced concurrently with the desktop version of mac OS is based on technologies developed between 19 at Ne XT, a company that Apple co-founder Steve Jobs created after leaving the company.