A multi-line chart displays telehealth device usage trends across patient age groups, comparing the frequency of desktop, tablet, and smartphone appointments. The code processes a CSV file, grouping patient ages by decade and counting device types. Three distinct SVG line paths, colored steelblue, green, and orange, represent each device category. The visualization uses d3.csv for data loading, d3.scaleLinear for x and y axes, d3.line for path generation, and d3.axisBottom and d3.axisLeft for the chart's axes.