This example demonstrates two fundamental D3.js path generators: `d3.line` and `d3.arc`. A black polyline connects four data points, with commented-out curve options like `d3.curveCardinal` and `d3.curveBasis` showing alternative interpolation methods. Beside it, three arc segments rendered via `d3.arc` form a partial donut chart with varying inner radii, fill colors, and a pad angle, all drawn as SVG paths on a 1600x800 canvas.