| Year | Event |
| 1978 | In June of 1978 Apple introduces Apple DOS 3.1, the first operating system for the Apple computers. |
| 1984 | Apple introduces System 1. |
| 1985 | Apple introduces System 2. |
| 1986 | Apple introduces System 3. |
| 1987 | Apple introduces System 4. |
| 1988 | Apple introduces System 6. |
| 1990 | Apple introduces System 7. |
| 1997 | Apple introduces Mac OS 8. |
| 1997 | Apple buys NeXT Software Inc. for $400 million and acquires Steve Jobs, Apples cofounder, as a consultant. |
| 1999 | Apple introduces Mac OS 9. |
| 2001 | Apple introduces Mac OS X 10.0 code named Cheetah. |
| 2001 | Apple introduces Mac OS X 10.1 code named Puma. |
| 2002 | Apple introduces Mac OS X 10.2 code named Jaguar. |
| 2003 | Apple introduces Mac OS X 10.3 code named Panther October 25, 2003. |