Every graphical User Interface component is implemented with the subclass of AWT Component class.

Button, Checkbox, Choice, List, MenuItem, and TextField classes provide the basic controls. These are the most common ways which users give instructions to the Java programs. When the user activates one of these controls -- by clicking the button or by pressing the Return in the text field, for example -- it posts the event (ACTION_EVENT). An object which contains the control can react to the event by implementing the method action().

When the basic controls are not appropriate, we can use the Canvas and TextArea classes to get the user input. The TextArea class simply provides the area to display or allow editing of several lines of a text. Create a subclass of the Canvas class to draw custom graphics to the screen -- in a paint program, an image processor, or a game, for example.

AWT provides two more handy components: the scrollbars and labels. Text areas automatically have the scrollbars, but we can use the Scrollbar class to make other kinds of areas scroll. Labels simply display uneditable, unselectable line of the text.

AWT provides two types of containers, both of which are implemented as subclasses of the Container class (which is the Component subclass). Window subclasses -- Dialog, FileDialog, and Frame -- provide the windows to contain components. Panels group components within the area of an existing window.