GUI: A graphical user interface.
widget: One of the elements that makes up a GUI, including buttons, menus, text entry fields, etc.
option: A value that controls the appearance or function of a widget.
keyword argument: An argument that indicates the parameter name as part of the function call.
callback: A function associated with a widget that is called when the user performs an action.
bound method: A method associated with a particular instance.
event-driven programming: A style of programming in which the flow of execution is determined by user actions.
event: A user action, like a mouse click or key press, that causes a GUI to respond.
event loop: An infinite loop that waits for user actions and responds.
item: A graphical element on a Canvas widget.
bounding box: A rectangle that encloses a set of items, usually specified by two opposing corners.
pack: To arrange and display the elements of a GUI.
geometry manager: A system for packing widgets.
binding: An association between a widget, an event, and an event handler. The event handler is called when the event occurs in the widget.