| 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. |
| 1995 | Apple allows other computer companies to clone its computer by announcing its licensed the Macintosh operating system rights to Radius on January 4. |
| 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 and becomes available March 24, 2001. |
| 2001 | Apple introduces Mac OS X 10.1 code named Puma and becomes available on September 25, 2001. |
| 2002 | Apple introduces Mac OS X 10.2 code named Jaguar and becomes available on August 23, 2002. |
| 2003 | Apple introduces Mac OS X 10.3 code named Panther October 25, 2003. |
| 2004 | Apple introduces Mac OS X 10.4 code named Tiger at the WWDC on June 28, 2004. |
| 2007 | Apple introduces Mac OS X 10.5 code named Leopard October 26, 2007. |
| 2008 | Apple introduces Mac OS X 10.6 code named Snow Leopard and MobileMe at the WWDC on June 9, 2008. |
