Mac OS 9 is the final major release of Apple's Classic Mac OS operating system. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as iTools and improved Open Transport networking. While Mac OS 9 lacks protected memory and full pre-emptive multitasking, lasting improvements include the introduction of an automated Software Update engine and support for multiple users.
Apple discontinued development of Mac OS 9 in 2002, transitioning all future development to OS X. Since that time, no updates have been released. The final updates to Mac OS 9 addressed compatibility issues with OS X while running in the Classic Environment and compatibility with Carbon applications. At the 2002 World Wide Developers Conference, Steve Jobs began his keynote address by staging a mock funeral for OS 9.
Read more about Mac OS 9: Features, Mac OS 9 and The Classic Environment, Version History, Compatibility, Availability