This visualization shows the global spread of COVID-19 by plotting circular markers on a world map, with each circle sized proportionally to the total reported cases for a country on March 25, 2020. The map uses a geoMercator projection with d3.geoPath to render country boundaries from TopoJSON. COVID-19 data from a CSV file is loaded with d3.csv, and circle radii are scaled using d3.scaleSqrt. An interactive range slider is present, though its current implementation only displays static text.