A yellow circle follows the mouse cursor across a full-window SVG canvas in this React application. The visualization tracks pointer movement using the SVG `onMouseMove` event, which updates the circle's `cx` and `cy` coordinates in real time. The circle's position is stored in React state and re-rendered on every mouse move, while its radius remains fixed at 50 pixels. The program uses React 16.9 with a custom event handler to create an interactive, responsive display that maps the cursor's screen coordinates directly to the SVG coordinate space.