Let's observe the process of data visualization in more detail. Here is the original chart of the monthly revenue for Products A, B, and C.

What's wrong with this chart? First, there are no descriptions: no chart title, no axis titles, and the values shown on the chart are not labelled. Without this information, it's impossible to know what this chart really means.

A much bigger problem is that the chart is presented in 3D. Putting charts in 3D may look cool, but this effect makes the data hard to read. For example, look at Product A's revenue for December. (Hint: It's the longest blue bar). Is it over 35 or below 35? It's actually just over 35, but that's hard to see on this chart.

Lastly, putting the timeline (January to December) on the vertical axis is a mistake. We're interested in revenue trends over time, so the time axis should be horizontal and the revenue axis should be vertical.

The next chart shows the same data, but we've fixed some of the presentation mistakes. Do you find it easier to read?

First, we got rid of the 3D effect. It's easier to compare the length of the bars. The timeline is on the horizontal axis. This is an improvement over the previous chart, but we can do better. Let's continue working on it.