This interactive bar chart visualizes the growth of iPhone users from 2008 to 2020, with the y-axis showing millions of users and each bar labeled with its exact value. Hovering over a bar highlights it, displays a dashed reference line at that bar’s value, and shows the numeric difference between the hovered year and every other year as text above the bars. The visualization uses d3.csv to load data, d3.scaleBand and d3.scaleLinear for scaling, d3.axisLeft and d3.axisBottom for axes, and d3 transitions for hover effects.