Initially focused on animation, early versions of Flash content offered few interactivity features and thus had very limited scripting capability.
More recent versions include ActionScript, an implementation of the ECMAScript standard which therefore has the same syntax as JavaScript, but in a different programming framework with a different associated set of class libraries. ActionScript is used to create almost all of the interactivity (buttons, text entry fields, pick lists) seen in many Flash applications.
A JavaScript library is a library of pre-written JavaScript controls which allow for easier development of JavaScript-based applications, especially for AJAX and other web-centric technologies.
Web development is a broad term for any activities related to developing a web site for the World Wide Web or an intranet. This can include e-commerce business development, web design, web content development, client-side/server-side coding, and web server configuration. However, among web professionals, "web development" usually refers only to the non-design aspects of building web sites, e.g. writing markup and coding.
