This bar chart displays the ten most populous cities in Nigeria for 2021, sourced from a CSV file by Niran Software Solution. Using React and D3 v5, the visualization renders horizontal bars via SVG, with the x-axis representing population and the y-axis listing city names. Population values are formatted using D3’s format function (e.g., “B” for billions), and tooltips show the exact population on hover. The axes and marks are built with custom components, using `scaleLinear` and `scaleBand` for scaling, while styling is defined in a linked stylesheet.