What does "Data Aggregator" mean?

Data Aggregator:

A Data Aggregator is a business that gathers information (about prospects or customers) from one or more sources, adds some value to it through processing of it, and sells the resulting data to businesses wishing to market to those prospects. Sometimes the "adding value" is done by giving the set of data to a company that then adds the information it has collected about those same prospects or customers to the data set, thereby updating it and "adding value" to it.

 Science Direct: Data Aggregators