# Line Graphs

## Timeline

Run charts are a type of line graph that are used to show changes in data over time. The time value should always be represented on the x-axis. Do not have more than three data sets shown in the graph, as your graph will become hard to read and process.

A useful feature to add to your run chart is the ability for users to zoom in and out to particular points of time represented on your graph.

### Multiple Variable Line Graph

When using multiple data series in a run chart, include a legend. See [Legends and Tooltips] for more information. Using different shapes for data points will also help distinguish multiple variables and increase accessibility.

For multiple variables, use a different colour for each line, and make sure there is enough contrast between them so they are easily distinguishable.

## Area Graphs

Area graphs are line graphs that can be used to represent quantitative data. You can use a stacked area graph to represent a part-to-whole relationship between data series. Use a lower opacity if the series overlaps so all series can be seen. Area charts can also be used to emphasize visual volume for a single data series of discrete objects.

Area graphs should be filled in with the same colour as the line, but at 15% opacity.