JavaScript is a scripting or programming language that allows you to implement complex features on web pages — every time a web page does more than just sit there and display static information for you to look at — displaying timely content updates, interactive maps, animated 2D/3D graphics, scrolling video jukeboxes, etc. It is the third layer of the layer cake of standard web technologies, two of which (HTML and CSS), JavaScript is a scripting language that enables you to create dynamically updating content, control multimedia, animate images, and pretty much everything else.