Drill-through can be described as the act of exploring related information. Also, this can be described as the act of moving between related data via a link of some kind. Most specifically, drill-through usually exploits a relationship between master and detail information. By clicking on a master item in the master information, the details of the clicked or selected item are then displayed or otherwise made available.
Drill-through is a very important feature supported out of the box by Cognos TM1. Out of the box, functionality is referring to abilities or features that the default install of Cognos TM1 provides. This functionality provides business value with little or no custom programming or development effort required.