This bar chart displays the population of the top 10 most populous countries, with data from the 2018 United Nations World Population Prospects estimate. It builds on a basic bar chart example by customizing the axes: the y-axis removes its default domain and tick lines, while the x-axis uses a custom tick format that converts abbreviations (G to B) and draws horizontal gridlines via negative tick sizes. The chart is rendered using D3 v5's `scaleLinear`, `scaleBand`, `axisBottom`, and `axisLeft` within an SVG, with styling applied through CSS classes.