Two reusable D3 legends demonstrate how to encode data through color and size. A color legend maps ordinal fruit names to distinct hues using `scaleOrdinal`, while a size legend translates a quantitative scale from 0 to 10 into circle radii via `scaleSqrt`. Both legends render as SVG groups with labeled ticks, using `selection.merge` to update existing elements efficiently. The examples show legend construction with configurable spacing, text offsets, and tick counts for flexible chart annotations.