A pie chart visualizes the distribution of employees across departments in an HR dataset. It shows the relative counts for each department as colored slices with hover tooltips revealing exact values. A legend identifies each department's color. Built with D3 v7, the code loads CSV data, aggregates counts using `d3.rollup`, and renders the chart with `d3.pie()` and `d3.arc()`, applying an ordinal color scale and SVG elements for the slices and legend.