This example demonstrates basic SVG shapes by rendering two circles in a web page. The first circle appears with default black fill, while the second uses an explicit red fill, showing how SVG handles default and specified color properties. The visualization relies on the native SVG API through inline `<circle>` elements and standard attributes like `cx`, `cy`, `r`, and `fill`. No external libraries or data sources are used; the rendering is purely declarative SVG markup embedded directly in the HTML document.