SVG Fundamentals
A concise demonstration of the SVG rendering approach in D3 v3, showing a single circle element styled with the default black fill. The example uses the SVG `<circle>` tag with `cx`, `cy`, and `r` attributes positioned at coordinates (50, 50) with a radius of 50, placed directly within an `<svg>` container in the HTML body. This serves as a minimal, foundational illustration of how SVG shapes are constructed and rendered in a browser context, highlighting the declarative nature of the vector graphics format without any additional D3 APIs or data binding.