A Brief Overview of Macromedia Flex

Macromedia Flex is a server component that enables you to create rich presentation layers for Internet applications. Interfaces built in Flex rely on Macromedia Flash Player for display on client systems. The essential components of Flex are:
An XML language (MXML) used to describe the application interface.
An ECMA scripting language (ActionScript) used with MXML to handle user and system events or to construct complex data models.
A class library
Runtime services
A compiler that generates SWF files from MXML files.