Tableau allows you to embed visualizations in the tooltips that are dynamically filtered as you hover over different marks. Often referred to as Viz in Tooltip, this greatly extends the interactivity available to end users, the ability to drill down to the details, and the ability to quickly see data in different ways.

In the preceding screenshot, the following tag was added to the tooltip by selecting Insert | Sheets | Categories:

<Sheet name="Categories" maxwidth="300" maxheight="300" filter="<All Fields>">

This tag, which you may edit, tells Tableau to show the visualization in the Categories sheet as part of the tooltip. The maximum width and height are set to 300 pixels by default. The filter indicates which field(s) act as a filter from the sheet to the Viz in Tooltip. By default, <All Fields>, means that all dimensions in the view will act as filters. However, you may specify a list of fields to specifically filter by one or more dimensions that are present in the view (for example, <Department>, <Category>).

Notice the final view with the tooltip:

Consider the many possibilities of the Viz in Tooltip:

• Drill down into details.
• It can show different aspects of the data (for example: geographic location as a
  Tooltip for a time-series).
• It allows the end user to see parts of the whole within a broader context.
• Much more