This example demonstrates a simple scatter plot of age versus salary for four sample data points, using circles positioned by linear scales. It renders to an SVG element with D3 v7 for the data-driven graphics and axes. The code also includes a React component that displays a "Hello D3 & React" message, showing integration between the two. The chart is static, with axes generated via `d3.axisBottom` and `d3.axisLeft`, and margins applied within the 600x400 viewport.