How Excel Charts Work A chart has an x-axis range and a y-axis range to show the correlation between two different data sets. The x-axis is the horizontal category line.

Naming Basics Best practice recommendations are to create a chart placing independent variables on the horizontal, x-axis and dependent variables on the vertical, y-axis.

If you want to add labels to the bubbles in an Excel bubble chart, you have to do it after you create the chart. Mary Ann Richardson explains what you need to do to add a data label to each bubble.