Left axis shows the difference in the calculated free energies of dissociation.

The vertical axis shows the proportion of energy transmitted through the Earth's atmosphere.

The horizontal axis shows the surface temperature of the stars.

The vertical axis from the fountain of water to the altar with the blood show the testimonies of spirit as cited in John, 5:97.

The long axes of the feldspar grains show a preferred orientation in some places.

The horizontal axis shows average family income, as measured by free-lunch eligibility.

The vertical axis shows the average test score.

The horizontal axis shows family income, the vertical axis shows test scores.

One axis of the chart shows the specific categories being compared, and the other axis represents a discrete value.

A common example would be that one axis shows hours in a day, the other days in a year.