This example demonstrates interactive brushing on a small scatter plot of weight and height data from a CSV file. Users drag a rectangular brush region to highlight data points, turning selected circles red and unselected ones blue. The visualization uses D3 v6 with an SVG rendering, a linear scale for both axes, and d3.brush to manage the selection. Points are positioned using transitions and axes are rendered with d3.axisLeft and d3.axisBottom.