The 4 Applications that were released were:
1. iTunes
2. iMovie
3. iPhoto
4. iDVD
All of these were created to run on OS 9 until OSX came out.
All Mac OSX Releases (in order):
-Mac OS X Server 1.0 "Hera"
-Mac OS X Public Beta "Kodiak"
-Mac OS X 10.0 "Cheetah"
-Mac OS X 10.1 "Puma"
-Mac OS X 10.2 "Jaguar"
-Mac OS X 10.3 "Panther"
-Mac OS X 10.4 "Tiger"
-Mac OS X 10.5 "Leopard"
-Mac OS X 10.6 "Snow Leopard"
-Mac OS X 10.7 "Cougar" (still in development, scheduled for 2011 release)