ActionScript is a scripting language that gives greater control over creating Flash movies by allowing for programming and scripting. It first appeared in Macromedia Flash 5 and has become more user-friendly through updates. ActionScript allows viewers more control over how they view Flash movies by enabling buttons like play and pause. In Flash games, ActionScript is used to program any movements or actions that occur within the game. Examples can be found on sites like ActionScript.org and Newgrounds.com.