This bar chart ranks countries by their GDP in billion USD, with bars sorted from largest to smallest and a tooltip on each bar showing the exact value. The visualization is built with D3 v7, using `d3.csv` to load the data from a remote gist, and `d3.scaleBand` for the categorical x-axis plus `d3.scaleLinear` for the numeric y-axis. Rotated country labels on the bottom axis and horizontal grid lines from `d3.axisLeft` aid readability.