What could be the simplest way to define what a drill is?

Drilling is a method that enables us to switch from an aggregative data display to a more detailed level of data, while keeping the data in the same context.

A straightforward answer for what keeps the data in the same context would be: the use of the relevant data hierarchy and determining whether it is a time, geographical, or product hierarchy. The hierarchy can also be costumed, and as long as the business user explores the data in a drill path that makes sense to him or her, it's only a matter of defining it.

For example, a business analyst would like to understand why the sales were higher in a particular year than another year's sales. Is it because a particular product was sold? Or as it because a certain sale campaign was operated successfully?

A team manager analyzes the overall time report and verifies that there were no working hour exceptions, but when he drills to the employee level, he notices that some team...