An interactive bar chart displays the 2018 Stack Overflow popularity ratings for ten programming languages, with each bar labeled by its percentage value. Hovering over a bar highlights it, increases its width, draws a dashed threshold line at that language's value, and reveals each bar's percentage difference relative to the highlighted language. The visualization is built with D3 v5, using `scaleBand` and `scaleLinear` for axes, SVG rects for bars, and transitions triggered by mouseenter and mouseleave events. Data comes from a local `data.js` file, with styling handled by an external stylesheet.