The phrase "rich source" refers to a plentiful or abundant supply of something. It can be used in various contexts, such as describing an area that has a lot of natural resources, like minerals or fossil fuels, which are valuable and can generate wealth for the region. In another sense, it could refer to a person who comes from a wealthy family background, with access to financial resources that others may not have. The phrase is also used in data analysis, where "rich source" refers to a dataset that contains detailed information about an individual or group of individuals, providing valuable insights into their behavior and preferences. In summary, the term "rich source" implies abundance, value, and potential for generating wealth or providing useful information.