ActionScript is a scripting language similar to JavaScript. It is used for Adobe Flash and Adobe Flex.
An example Hello World program in ActionScript 3.0:
package com.example { import flash.text.TextField; import flash.display.Sprite; public class Greeter extends Sprite { public function Greeter() { var txtHello:TextField = new TextField(); txtHello.text = "Hello World"; addChild(txtHello); } } }