What is a drill-down chart?
Drilling down gives you a way to reveal additional levels of detail within a chart. For example, suppose you want to report on sessions by country, and sessions by city. Rather than include two charts in your report, you can include a single chart with drill-down enabled. When drill-down is enabled on a chart, you can.
What is drill-down visualization?
Visualization drill downs allow users to create hierarchies in visualizations so that users can click on a component of a chart and "drill in" to explore the data within that piece of the visualization.
What is drill-down UX?
The drilldown pattern allows users to select an item from a grid to see more details in place of the grid. This page explains how you can use this pattern in your interface, and walks through the design structure in detail.