This example demonstrates two legend styles for D3 visualizations: a color legend mapping ordinal categories to colors, and a size legend mapping a square-root scale to circle radii. The color legend displays four fruit labels next to colored circles, while the size legend shows five tick values with circles whose areas scale with the data. Both legends are built as reusable SVG components using D3's selection API, with `scaleOrdinal` and `scaleSqrt` defining the mappings. The code uses `.call()` to invoke the legend functions and `merge()` to handle updates efficiently.