This example demonstrates a circle that follows the mouse cursor within an SVG canvas. It shows interactive tracking by rendering a single circle whose position updates based on mouse movement events. The implementation uses React with the `useState` and `useCallback` hooks to manage and update the circle's coordinates. Mouse movement is captured via the SVG's `onMouseMove` event handler, which extracts the `clientX` and `clientY` properties. The circle is drawn using ReactDOM's rendering into an SVG element, with a fixed radius of 30 pixels within a 960x500 viewport.