This example presents the most basic possible SVG visualization: a single gray circle rendered inside an HTML page. The code uses a minimal standalone HTML document with an inline `<svg>` element, placing the circle without any data binding or axes. It demonstrates the foundational structure for a D3-style visualization gallery entry, showing how raw SVG shapes can be used to create simple graphics before adding interactive features. The example relies purely on native SVG and HTML5 APIs, with no external JavaScript libraries or data sources.