This example displays a simple world map rendered as an SVG, with each country depicted as a dark green path with a semi-transparent white stroke. The visualization uses D3 to generate the map, though the specific geographic data is not loaded in the provided code. A separate interactive feature adds a small green circle that, when hovered, reveals an absolutely positioned tooltip displaying the text "I'm a circle!" The tooltip’s position updates based on mouse movement using the D3 selection API and event coordinates. The map’s styling is defined in an external CSS file.