This bar chart displays the population of the top 10 most populous countries, based on 2018 estimates from the United Nations World Population Prospects. It visualizes both bars and circles for each country while demonstrating how to customize D3 axes. Using D3 v5, the code applies `d3.scaleLinear` and `d3.scaleBand` for scales, `d3.axisBottom` and `d3.axisLeft` to generate axes, and custom tick formatting with `d3.format` to abbreviate numbers. Axis gridlines extend across the chart, and the default axis lines and ticks are removed for a cleaner look.