Imagine you're working for an established company that already has defined customers, and prospective customers. Now imagine your have a database for doing all kinds of analysis on your customers: Their name, amount you've sold them over any given period, where they're located, what product(s) they've purchased, any open sales opportunities, leads, or marketing campaigns for a respective company etc... Where does this data come from (what data sources)? How does this get into a database?