Glossary » widget
any of a variety of interactive objects in a graphical user interface. Widgets are generally meant to metaphorically suggest real-world controls. A widget can be a button, a menu, a scrollbar. It can refer to a more complex object like a window or dialog box which also contains other widgets. Widgets are visual. They have some behavior: they respond to input and they change what they’re displaying.
User interface toolkits provide programmers with easy ways to display and use widgets and sometimes to design their own widgets.
Widgets are the most obvious visual contribution of GUIs. They’re ideally intuitive. They’re fun. They’re familiar. They occur again and again so users become accustomed to using them.