A stacked bar chart compares total sales by product sub-category across three customer segments (Consumer, Corporate, and Home Office). Mouse hover on a legend item highlights that sub-category’s segment breakdown while dimming the others, with tooltips detailing exact sales values. The visualization uses D3.js (v3.5.5) with the `d3.layout.stack` API, SVG rendering, and the `d3.legend` and `d3.tip` libraries, drawing sales data from a CSV file.