The component tray represents components that do not otherwise provide a visible surface at design time and provides a way for users to access and set the properties of those components.

Some types of components, such as a System.Timers.Timer, may not have a user interface that can be viewed at design time. These components are usually represented by icons that are shown in the component tray.

The component tray is a rectangular region displayed at the bottom of the design view window while in design view mode, once it is active. The component tray becomes active in design view after a component that is displayed in the component tray has been added to or is part of the current document.