This interactive histogram displays the distribution of GDP per capita data across countries from 1960 to 2019, allowing users to switch between data columns or adjust the number of bins via a dropdown menu and numeric input. Built with React and D3 v5, it uses `d3.histogram`, `d3.scaleLinear`, and `d3.axisBottom`/`d3.axisLeft` to render SVG bars with smooth transitions, while tooltips reveal bin ranges and frequencies on hover.