A bar chart of twenty values rendered as SVG rectangles uses D3.js version 4.5.0 to display a dynamic tooltip on mouseover. The tooltip is created by appending a text element to the SVG at the bar’s position, showing the data value, and removed on mouseout. Clicking a bar triggers a sorting animation using `transition().delay()` and `duration()` to reorder bars by value. Bars also change color to orange on hover via CSS.