There are three main elements in a graph :

- a vertical axis (the y- axis)

- a horizontal axis (the x-axis),

- at least one line or set of bars.

To understand a graph, do the following:

1 Read the title of the graph.

2 Read the labels and the range of numbers along the side (the scale or vertical axis), and the information on the bottom (horizontal) axis.

3 Determine what units the graph uses. This information can be found on the axis or in the legend.

4 Look for patterns, groups and differences.

Here is a graph from the Health section of the Atlas:

Above is a complex graph showing life expectancy and spending on health care
for the thirty countries with longest life expectancies.