A line chart displays AT&T's annual user counts from 2015 to 2021, with the x-axis showing years and the y-axis showing users. The visualization uses D3 v5's `scaleTime`, `scaleLinear`, `axisBottom`, `axisLeft`, and `line` APIs to render an SVG. Data is loaded from a CSV hosted on GitHub Gist via `d3.csv`, with years parsed as `Date` objects and user counts converted to numbers. The chart includes labeled axes, a title, and a thick blue line path, with grid lines styled via CSS.