An area chart displays the average car price per year, drawn as a smooth steel-blue filled region with an overlaid line and dots for readability. It uses D3 v7 with SVG rendering, grouping a CSV dataset of cars by `Year` and computing the mean `Price` via `d3.rollups`. Scales (`d3.scaleLinear`), axes (`d3.axisBottom`, `d3.axisLeft`), and generators (`d3.area` with `d3.curveMonotoneX`) structure the visualization, with axes labeled for year and average price in USD.