A red circle follows the mouse cursor across a full-window SVG canvas, with live text displaying the current cursor X and Y coordinates. Built with React’s `useState` and `useCallback` hooks, the application uses an `onMouseMove` event handler to update the circle's `cx` and `cy` attributes. The code also loads cardiovascular disease data from a CSV file using `d3.csv`, logging the row count and feature count to the console while the React interface handles rendering.