This document provides an overview of Rich Internet Applications (RIAs) and the Flex framework. It defines what an RIA is, describes common RIA tools like AJAX and Flex, and explains the anatomy and key features of RIAs. The document then focuses on Flex, explaining what Flex is, how it compares to Flash and AJAX, and how the Flex development process works using MXML, ActionScript, and compiling into SWF files. Examples of Flex applications and resources for learning more about Flex are also provided.