This heatmap displays a 10x10 grid of values ranging from 1 to 100, colored on a white-to-teal scale using d3.scaleLinear. Each cell represents a combination of group (A-J) and variable (v1-v10) from a CSV dataset loaded via d3.csv. On mouse enter, individual rectangles change their fill color to black through React’s onMouseEnter event handler. The SVG rendering uses d3.scaleBand for x and y positioning, with React components managing the data fetching and mark generation.