A React application tracks the mouse and renders a circle that follows it across an SVG canvas. The component uses React hooks—`useState` to store the mouse position and `useCallback` for the move event handler. The SVG element listens for `onMouseMove` events, updating the circle's `cx` and `cy` coordinates based on the client X and Y values. The circle has a fixed radius of 30 pixels, and the viewport is 960 by 500 pixels. React DOM renders the app into a root div, with no external data source.