An area chart displays monthly sales data from a CSV file, with a monotone-smoothed line and translucent fill. The time series x-axis uses UTC date parsing and monthly tick formatting. Built with d3 v7, the chart constructs SVG output via the `areaChart` fluent API, `d3.scaleUtc`, `d3.axisBottom`, and `d3.curveMonotoneX`, rendering the data through d3.select and the charting function.