Data warehouse assembles data dispersed in various data sources across the enterprise and helps business stakeholders manage their operations by making better informed decisions. Most organizations have multiple data stores: relational databases, spreadsheets, mainframes, mail systems or even paper files. Each of these data stores tends to serve a subset of the enterprise. Data warehouse attempts to overcome this limitation by combining all relevant data and by allowing managers to view their business from many different angles.
This is a companion discussion topic for the original entry at https://blog.toadworld.com/overview-of-data-warehousing-concepts