Chart Type for Trend Over Time. Keywords: trend, time-series, line, growth, timeline, progress. Best Chart: Line Chart. Secondary Options: Area Chart, Smooth Area. When to Use: Data has a time axis; user needs to observe rise/fall trends or rate of change over a continuous period. When NOT to Use: Fewer than 4 data points (use stat card); more than 6 series (visual noise); no time dimension exists. Data Volume Threshold: <1000 pts: SVG; ≥1000 pts: Canvas + downsampling; >10000: aggregate to intervals. Color Guidance: Primary: #0080FF. Multiple series: distinct colors + distinct line styles. Fill: 20% opacity. Accessibility: AA — Differentiate series by line style (solid/dashed/dotted) not color alone. Add pattern overlays for colorblind users.. A11y Fallback: Dashed/dotted lines per series; togglable data table with timestamps and values. Library: Chart.js, Recharts, ApexCharts. Interactive Level: Hover + Zoom.