This example shows a single circle that follows the mouse cursor across an SVG canvas. The circle begins at the center of a 960-by-500 pixel viewport and updates its position in response to every mousemove event. The application is built with React 16.9, using the useState and useCallback hooks to manage and update the mouse coordinates. Rendering is handled declaratively through ReactDOM, with the circle’s cx and cy attributes bound directly to the current mouse position state.