Now that we've considered how formatting works in Tableau, let's take a look at some ways in which formatting can add value to a visualization.

When you apply custom formatting, always ask yourself what the formatting adds to the understanding of the data. Is it making the visualization clearer and easier to understand? Or is it just adding clutter and noise?

In general, try a minimalistic approach. Remove everything from the visualization that isn't necessary. Emphasize important values, text, and marks, while de-emphasizing those that are only providing support or context.

Consider the following visualization, all using default formatting:

The default format works very well. But compare that to this visualization:

Both the preceding diagrams are showing sales by the quarter, filtered to the office supplies department. With the exception that the top view has the department field on Columns in an attempt to make it clear that only office supplies sales are being shown, the field arrangement for the two views is exactly the same. The first view uses the default formatting.

Consider some of the customizations in the second view:

• Title has been adjusted to include the department name.
• Sales has been formatted to be shown using a custom currency with two decimal places and units of millions. This is true for the axis and the annotations. Often, a high level of precision can clutter visualization. The initial view of the data gives us the trend and enough detail to understand the order of magnitude. Tooltips or additional views can be used to reveal detail and increase precision.
• The axis labels have been removed by right-clicking the axis, selecting Edit Axis, and then clearing the text. The title of the view clearly indicates that you are looking at Sales. The values alone reveal the second axis to be by the quarter. If there are multiple dates in the data, you might need to specify which one is in use. Depending on your goals, you might consider hiding the axes completely.
• The gridlines on Rows have been removed. Gridlines can add a value to a view, especially in views where being able to determine values is of high importance. However, they can also clutter and distract. You'll need to decide, based on the view itself and the story you are trying to tell, whether gridlines are helpful.
• The trend line has been formatted to match the color of the line, though it is lighter and thinner, to de-emphasize it. Additionally, the confidence bands have been removed. You'll have to decide whether they add context or clutter based on your needs and audience.
• The lines, shading, and boxes have been removed from the annotations to reduce clutter.
• The size and color of the annotations have been altered to make them stand out. If the goal had been to simply highlight the minimum and maximum values on the line, labels might have been a better choice, as they can be set to display at only Min/Max. In this case, however, the lower number is actually the second-lowest point in the view.
• Axis rulers and ticks have been emphasized and colored to match the marks and reference line (axis rulers are available under the Lines option on the Format window).

Formatting can also be used to dramatically alter the appearance of visualization. Consider the following chart:

This visualization is nearly identical to the previous view. However, shading has been applied to the worksheet and the title. Additionally, fonts were lightened or darkened as needed to show up well on a black background. Some find this format more pleasing, especially on mobile devices. If the view is to be embedded into a website with a dark theme, this formatting may be very desirable. However, you may find some text more difficult to read on a dark background. You'll want to consider your audience, the setting, and mode of delivery as you consider whether such a format is the best for your situation.