This example demonstrates how an SVG mask can selectively reveal or hide parts of a shape, using a path as the mask. A single green circle is rendered, partially obscured by a jagged mask path defined in SVG’s `<defs>` and applied via the `mask` attribute. The code uses raw SVG elements, including `circle`, `path`, and `mask`, with styling provided by inline CSS. The mask’s fill color (`#555`) controls the transparency region, showcasing a basic technique for clipping or layering vector graphics without external libraries.