According to webopedia, in information technology, a drilldown can be defined as follows:
"To move from summary information to detailed data by focusing in on something."
Splunk offers the ability to initiate a search by clicking on a (row in a) table or (a bar in) a chart. This search will be based on the information that you clicked on in the table or chart. This search that dives deeper into the details of a selection is known as a drilldown and is displayed in a separate window from the original search results.
As an example, we can use one of our earlier Splunk search examples (shown next):
sourcetype=csv 2014 "Current Forecast" "Direct" "513500" | rename May as "Month" Actual as "Version" "FY 2012" as Year 650693NLR001 ...