The Highlight action is also used quite often. From one or multiple Source Worksheets, you can highlight fields on one or multiple Target Worksheets. The next screenshot is an example of a Highlight Action where hovering over a category from one of the two bottom Worksheets automatically highlights it on both visualizations:

In the preceding screenshot, we hover over the Furniture category in the Profit Evolution by Category Worksheet, and thanks to the Highlight Action, we can easily spot this category on the Profit by Sub-Category Worksheet.

As for the Action filter, you can specify what fields will be highlighted. 

When you add a Highlight action, a new window opens where you can configure it. Here's the configuration window of the preceding Highlight example:

In the configuration window, you can specify the following:

• The Name of the Action — here Highlight Categories.
• The Source Sheets—in the example, the Action sources are both Profit Evolution by Category and Profit by Sub-Category.
• The trigger, a Hover on a Mark in the example.
• The Target Sheets—the same as the Source here, as we want to highlight both Worksheets at the same time.
• The Target Highlighting fields (by default, All Fields from the source are highlighted on the Targeted Worksheets, but it's possible, by using Selected Fields, to choose which ones to use) — in the example, we want to highlight only the Category. 

The next Action, Go to URL..., is a great way to add interaction with the outside world to Tableau.