This interactive grouped bar chart visualizes average fitness levels for males and females across six age groups, from 18-25 to 46-50. Users can click the legend to filter bars by gender, and hover over any bar to see a tooltip with the exact average value. The visualization uses the D3.js library with `scaleBand`, `scaleLinear`, `axisBottom`, and `axisLeft` APIs to construct the chart, while grouping data by age range and gender. It also features a custom tooltip and interactive legend filtering, with animated transitions on mouse interactions.