Definition - What does ActionScript mean?
Originally introduced by Macromedia for its Flash authoring tool, ActionScript is now developed and supported by Adobe Systems. The language is open source and both an open source compiler (as part of the Adobe Flex suite) and a virtual machine (Mozilla Tamarin) are available.
Techopedia explains ActionScript
With the introduction of Flash 4 in 1999, ActionScript 1.0 was born as a programming language and Flash became truly interactive. Major revisions, 2.0 with object-oriented features in 2003 (for Flash Player 7) and 3.0 (for Flash Players 9 and 10), followed. Version 3.0 was a major restructuring of the language and a new virtual machine (AVM2) was introduced to run ActionScript 3.0 content.
ActionScript allows for rich content to be developed and placed on websites as embedded SWF files, compared to static, noninteractive images and videos. ActionScript popularized single- and multi-player Flash games, engaging user-aware navigation and rich video content, and allowing content to change based on user interaction or on the frame of the movie being played.
With Flash Player 10, a new sound API makes the custom creation of audio in Flash applications possible.