This example demonstrates fundamental D3.js selection and DOM manipulation techniques within a React starter setup. It uses `d3.select` and `d3.selectAll` to target the `h1` element, changing its text, adding a class attribute, and styling it red. The code also appends a new paragraph to the body via `d3.select('body').append('p')`. Running with D3 v4, the visualization shows how D3 can directly manipulate HTML elements alongside a standard webpage structure.