This line chart shows the number of passengers using different airlines from 2005 to 2019, with each airline’s trend encoded by a distinct color. The vertical axis represents passenger counts, the horizontal axis indicates the year, and it includes both domestic and international flights. It uses d3.v4 with SVG rendering, where the `line()` generator creates the paths and `d3.scaleTime` maps the time data. The design includes axis labels, a legend to identify airlines, and smooth animated transitions via `transition.attrTween` to update the lines.