A yellow circle follows the mouse cursor across a blank SVG canvas, with its position updating in real time to track pointer movement. The visualization demonstrates React state management for interactive graphics, using React hooks `useState` and `useCallback` to handle mouse events. The `onMouseMove` handler on the SVG element captures cursor coordinates, which are then used to set the circle's `cx` and `cy` attributes. Built with React 16.9.0 and D3.js v6, the example renders entirely through React's virtual DOM without direct D3 DOM manipulation.