Carbon (API)
Carbon is one of Apple Inc.'s procedural application programming interfaces (APIs) for the Macintosh operating system. It provides C programming language access to Macintosh system services. Carbon provides a good degree of backward compatibility for programs to run on the now-obsolete Mac OS 8 and 9, however these systems are no longer actively supported since Apple released the final OS 9 update in December 2001.
Read more about Carbon (API): Overview, Evolution and Backward Compatibility, Today, Transition To Cocoa, Architecture, Event Handling, Timers