This D3.js area chart visualizes car sales data from 2019 to 2021, grouped by car type, with three semi-transparent filled areas representing each year's sales figures. The chart uses the d3.area component with monotone curve interpolation to render smooth area paths, while d3.scaleBand and d3.scaleLinear handle x- and y-axis positioning. Data loads from a text file via d3.text, which is parsed and transformed into the chart's structure. A legend with colored rectangles identifies the three years, and all elements render as SVG within an 800×400 viewport.