A horizontal bar chart displays population figures for the top 10 most populous countries, with data derived from the 2018 United Nations World Population Prospects estimate. The visualization customizes both axes: the y-axis removes its domain and tick lines, while the x-axis uses a `d3.axisBottom` scale with a tick format that converts gigayears to billions, and gridlines extend across the plot. The chart is rendered as SVG using D3 v5, with countries arranged on a `d3.scaleBand` y-axis and bars drawn as `rect` elements.