This visualization displays global population growth over time using a filled area chart, with the x-axis representing years and the y-axis showing population in billions. The chart uses D3 v5's `scaleTime`, `scaleLinear`, and `area` generator with a basis curve to create a smooth, maroon-filled region beneath the trend line. Axes are rendered via `axisBottom` and `axisLeft`, with grid lines and custom tick formatting converting gigayears to billions. Data comes from a CSV file loaded via `d3.csv`, containing world population figures by year through 2015.