The ArcGIS API for Flex provides built-in MXML visual components and containers.
Components, sometimes referred to as controls, are interface widgets that can be added to your application. Apache Flex components include Button, Label, Form, and TextInput. ArcGIS API for Flex components include ArcGISDynamicMapServiceLayer, ArcGISTiledMapServiceLayer, and ArcIMSMapServiceLayer.
Tip:MXML is typically used for layout purposes; however, you can also use ActionScript 3.0 to create and modify components. To see Flex components in action, check out the Tour de Flex application.
Containers are layout tools that position the interface widgets or data in the application. Some example Apache Flex containers are Application, HGroup, VGroup, and BorderContainer; the ArcGIS API for Flex container is Map.
Containers provide a hierarchical structure that allows you to control the layout characteristics of child components. Components defined within a container are called children. At the root of any Flex application is a single container: the Application container.