Data is not actually extracted or moved from the host systems; instead, a 'view' is created using the appropriate tools to facilitate a business requirement.
The view can then be extracted and sent on using the pattern Bulk Data Replication if required. The view is typically a 'snap-shot' of a particular set of data that could be from multiple sources.
The data it is reporting on would be dynamic, so changes frequently.
The view could also be of data of a sensitive nature where some data may need to be masked. The original data is not updated, but this saves having to store many copies of the same data.