This bar chart displays the 2018 estimated populations of the top 10 most populous countries, sourced from the United Nations World Population Prospects 2017. It uses D3’s `scaleLinear` for the x-axis (population in millions) and `scaleBand` for the y-axis (country names), with bars rendered as SVG rectangles. The example demonstrates custom axis styling and builds on a prior bar chart tutorial, showing how to map data to visual properties via D3’s scales and selection API.