This bar chart visualizes the popularity of various programming languages based on 2019 Stack Overflow survey data. It uses D3.v5 to render an SVG bar chart with a dark background, where each bar’s height corresponds to a percentage value. The chart includes axes, gridlines, and a title. On mouse hover, it displays the difference between the hovered bar’s value and each other bar, using a dashed line and divergence labels. The visualization relies on `d3.csv`, `d3.scaleLinear`, `d3.scaleBand`, and `d3.axisLeft`/`d3.axisBottom` for scaling and rendering.