An interactive React application displays a single circle that follows the mouse cursor across an SVG canvas. The code tracks pointer movement through React’s `useState` and `useCallback` hooks, updating the circle’s `cx` and `cy` attributes on every mouse event. Built with React 16.9 and rendered via ReactDOM, it demonstrates a simple state-driven visualization without any external animation or data libraries. The SVG viewport is fixed at 960 by 500 pixels, with the circle starting at the center until the user moves the mouse.