The Difference between “Internal” and “External” Source Systems in Data Warehousing

data-warehousedatabase-designetlmaintenance

I am reading about data warehousing and I run into the concept of internal and external source systems.

Data are extracted from various internal and external source system files and databases.

Here is a supplementary figure of the concept

I couldn't clearly distinguish between the concept of internal and external.

Any explanation of the key difference?

Thank you,

Best Answer

You could get data from data providers - for example, geoip data from Maxmind, rating data from Moody's, device data from BlueCava. Those are all external systems. Systems used by the organization are internal systems.