This bar chart visualizes the popularity of programming languages from Stack Overflow's 2019 survey, with each bar labeled by percentage. Using D3.js v5, the SVG chart includes axes, gridlines, and a hover interaction: hovering a bar dims other values and displays the percentage difference relative to the selected bar via dynamically added text labels and a horizontal guide line. The code uses `d3.scaleLinear`, `d3.scaleBand`, `d3.axisLeft`, `d3.axisBottom`, and `transition` for animation.