Watson Explorer Engine enables users to query multiple data sources simultaneously and remotely, organizing their combined outputs into automatically-generated categories (clusters) on the fly. Sources can be web or intranet search engines, licensed feeds, databases, or search collections created with the search engine that is included in Watson Explorer Engine. Watson Explorer Engine can create search collections by crawling the web, file systems, many enterprise data repositories (email archives, database application, knowledge management systems, and so on), or your intranet.
For an explanation of how Watson Explorer Engine works internally, read the Functional Overview of a Search Application.