A bar chart displays the quarterly floating population of Gangnam District, South Korea, from 2019 to 2020, using a reversed linear y-axis scale so taller bars represent smaller totals. The visualization is rendered with D3 v6, reading data from a local CSV file via `d3.csv` and building SVG rectangles with `scaleBand` for the x-axis and `scaleLinear` for the y-axis, annotated with `axisBottom` and `axisLeft`.