widgets. - Widgets describe the structure and design of the UI, but are immutable Three Trees Widget Tree Element Tree RenderObject Tree - Live, mutable representation of the widget instances - Handles the lifecycle and state of widgets - Maintains the link between the widget and its corresponding render objec - Responsible for the layout and painting of the UI on the screen - Render objects define the size, position, and rendering of each widget - Render objects handle hit testing to detect user interactions and gestures.