This example shows a single yellow circle that moves across an SVG canvas in response to mouse movement. Built with React 16.9.0 and rendered via SVG, the circle is positioned using the `clientX` and `clientY` coordinates from the `onMouseMove` event, with initial state centered at (480, 250). The code uses React's `useState` hook to track mouse position and the ReactDOM `render` method to update the circle's `cx` and `cy` attributes dynamically.