The first version of Actionscript came out with the r elease of Flash 5 with the support of Object Oriented Programming (OOP) concepts. Programmers with C++ background were really excited about it because it made tasks for them much easier. Actionscript 2.0 was released in September 2003, which featured compile time type checking, the class-based inheritance, class-based syntax and more.
In June 2006, Actionscript 3.0 was released as a basic reformation of the language. It came out with more powerful and strongly object- oriented programming features. The salient features of AS 3.0 makes it much better than AS 2.0. AS 3.0 comes with many new classes, methods and support for namespaces, package and regular expressions for the ease of programmers. For example there is a class named Stage and it has a method frameRate. It lets the programmer set the frame rate of the movie dynamically. This is an improved feature in AS3.0 that was not possible in AS 2.0. AS 3.0 also replaces many methods like onClipEvent and getURL with newer ones and some methods and properties like attachMovie and _global have been just removed
With the development of more and more complex and near to reality applications, it becomes important that the application speed is fast enough. AS 3.0 is proven to be capable enough to provide good speed performance. It is estimated that AS3.0 is at least 10 times faster than AS2.0.
AS 3.0 includes a set of classes based on E4X specifications. These classes provide powerful and simple-to-use functionality if you want to work with XML data.
AS3.0 also provides new event handling system that is based on DOM event handling standard. It supports single event handling system instead of different event handling systems that were existed in previous versions of Actionscript.