This visualization displays customer counts per year from a small CSV dataset using a line chart. The D3.js v7 code loads the data with `d3.csv`, then applies a `scaleBand` for the x-axis and `scaleLinear` for the y-axis. The line is drawn with the `d3.line` path generator, using an SVG rendering approach within a designated chart container. The chart includes labeled axes for "Year" and "customers", with styling applied through a separate CSS file.