When ActionScript 2.0 was released - and later Flash 8 - it was exciting to see the new capabilities of the Flash player. But, the improvements of ActionScript 3.0 over ActionScript 2.0 are incredible. When I jumped in and started playing around with ActionScript 3.0 I discovered many significant changes, all for the better. The following is a list of improvements that, for me, were exciting to see:

• Improved Object Oriented support (internal, public, private, and protected class types).
• Improved event model; all events require listeners.
• MouseEvent.MOUSE_LEAVE (detect mouse exit from stage) - enough said.
• Performance - See PaperVision3D.
• Improved compile-time and run-time error reporting.
• DisplayList and MovieClip re-parenting and auto-depth management.
• int and uint Classes for non-floated numbers.
• XML is a built-in datatype
• Intervals replaced with Timers
• Built in “drawCircle” (or “drawOval”) method added for run-time elliptical shape-generation.

There’s a lot more as well, but these are just a few improvements that I was very pleased to see.