The beta's arrival marked some fundamental technical changes, most courtesy of an open source Darwin 1.2.1 core, including two features that Mac users and developers had been anticipating for almost a decade: preemptive multitasking and protected memory.

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.

[5][6][7][8] Early adopters had to turn to open source or shareware alternatives, giving rise to an active homebrew software community around the new operating system.

The poor state of the Carbon API contrasted with the relative maturity of Cocoa gave rise to an anti-Carbon bias among Mac OS X users.

[12] 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.