How Excel Draw a Chart

A chart is essentially an object that Excel creates upon request. This object consists of one or more data series, displayed graphically. The appearance of the data series depends on the selected chart type.

To create the chart shown in figure above, Excel performs a few straightforward steps. First, it extracts the text for the chart title from cell A1. Next, it examines the range of data (from $4,100 to $6,050) and uses it to set the valueor Y-axisscale. You'll notice that the scale starts at $0, and stretches up to $7,000 in order to give your data a little room to breathe. (You could configure these numbers manually, but Excel automatically makes common-sense guesses like these by looking at the data you're asking it to chart.) After setting the vertical scale, Excel adds the labels along the bottom axis (also known as the X-axis or category axis), and draws the columns of appropriate height.

A key point to keep in mind is that charts are dynamic. In other words, a chart series is linked to the data in your worksheet. If the data changes, the chart is updated automatically to reflect those changes.