1.4 Components Everywhere

"A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third parties [Szyperski]."

"In essence, the context is the container for all of the components. A container is a system that hosts components and provides a set of services that allow those components to be manipulated."

This manipulation can be at design time (in the IDE) or runtime (in the application server).

"A UI component, or control, is a component that provides specific functionality for interacting with an end user. Classic examples include toolbars, buttons, panels, and calendars."