External data (also called third party data) is all data you receive from outside of your own systems (both on-premise and cloud). External data may be open data from governments, second party data from partners, third party data you purchase from data aggregators, or commercial data from professional data providers.
In many cases, external data is used to enrich internal data within a company. External data enrichment describes this process of matching data from outside of an organization with data inside an organization. In order to correctly match internal and external data, you need a match key for each object in a database - or a fuzzy matching algorithm.
There are tens of thousands of data providers for external data. In general, you can classify external data providers into three (3) categories: