This interactive map visualizes course viewership data by country, using a dropdown menu to filter between different courses and an "All" option for aggregated totals. It renders a world map with D3 geoMercator projection, drawing D3 geoGraticule lines, geoPath land masses, and sphere background. Data is loaded via D3's csv and json from external sources, with circle markers sized using scaleSqrt based on view counts and tooltips displaying country and view totals. The React frontend updates the map and circles when a course is selected from the dropdown menu.