The Mac OS X Public Beta (internally code named "Kodiak") was the first publicly available version of Apple Computer's Mac OS X (now named macOS)operating system to feature the Aqua user interface. It was released to the public on September 13, 2000 for US$29.95. Its release was significant as the first publicly available evidence of Apple's ability to ship the long-awaited "next-generation Mac operating system" after the Copland failure. It allowed software developers and early adopters to test a preview of the upcoming operating system and develop software for the forthcoming operating system before its final release. It is the only public version of Mac OS X to have a code name not based on a big cat until the release of 10.9 Mavericks in 2013. The US version had a build number of 1H39 and the international version had build number 2E14.
The Public Beta succeeded Mac OS X Server 1.0, the first public release of Apple's new NeXTOpenStep-based operating system, which used a variant of the classic Mac OS's "Platinum" user interface look and feel. The Public Beta introduced the Aqua user interface to the world. Fundamental user interface changes were revealed with respect to fonts, the Dock, the menu bar (with an Apple logo at the center that was later repositioned to the left of the menu bar and made an active interface element). System icons were much larger and more detailed, and new interface eye candy was prevalent.
The Public Beta included many of the standard programs bundled with macOS today, such as TextEdit, Preview, Mail, QuickTime Player and Terminal. Also included with the Public Beta, but not in any subsequent versions of Mac OS X, were a simple MP3 player (iTunes had not yet been introduced), Sketch, a basic vector drawing program demonstrating features of Quartz, and HTMLEdit, a WYSIWYG HTML editor inherited from WebObjects.
The Mac OS X Public Beta was expired on May 14, 2001; approximately two months after the release of Mac OS X 10.0, the completed version of the operating system released in March 2001. As a result, it will not run on later PowerPC-based Macintosh computers released after early 2001, nor on current Macintosh hardware, which uses the x86 and ARM64 processor architectures. Using the Mac OS X Public Beta on compatible equipment today requires setting the hardware clock to a date prior to the expiration date.
The expiration date forced users to purchase a copy of the final release rather than continuing to use the Public Beta, as well as reassured industry observers skeptical after the Copland and Rhapsody failures that Apple would actually release a next-generation operating system this time. Owners of the Public Beta version were entitled to a $30 discount on the price of the first full version of Mac OS X 10.0. Only the Aqua GUI and related components of the Public Beta were subject to expiry; the underlying Darwin command-line based OS continued to function.
Singh, Amit (December 2003). "What is Mac OS X?". One relatively common notion about Mac OS X seems to be that there's not a lot of software for it. While it is true that the quantity of software available for Mac OS X is not as large as, say, that on Windows or Linux...
Siracusa, John (April 2001). "Mac OS X 10.0". Ars Technica. p. 16. The general consensus is that Cocoa applications are superior to Carbon applications in terms of support for OS X features, multitasking ability, and interface responsiveness. Whether this is due to any inherent superiority of the technologies in Cocoa or is merely a byproduct of the immaturity of the Carbon impelmentation (as compared to Cocoa/OpenStep, which has been around for years) is still open for debate