Line Chart

A line chart connects data points in order — almost always over time — so the slope of the line shows how fast something is rising or falling. It turns a sequence of monthly revenues or daily temperatures into a single readable trend you can trace with your eye.

Use it only when the points have a meaningful order, since the connecting line implies the values flow continuously from one to the next; connecting unordered categories with a line is misleading. Unlike a bar chart, a line chart's vertical axis need not start at zero, because here you are reading the shape of the change rather than comparing total heights.