This example shows a bar chart of language frequencies, with bars colored blue by default and highlighted in green for French and Italian. The chart is rendered as SVG using D3 v4, with an x-axis for language names and a y-axis for frequency percentages. The code loads tab-separated data from `languages.tsv` using `d3.tsv`, scales the data with `d3.scaleBand` and `d3.scaleLinear`, and draws rectangles via `g.selectAll(".bar").enter().append("rect")`. Hovering a bar turns it dark red, as defined by the `.bar:hover` CSS rule.