A Data Warehouse is a relational database designed for queries and data analysis, decision-making and business intelligence activities more than for transaction processing or other traditional uses of databases.
In addition to a relational database, a Data Warehouse environment integrates a data extraction, transport, transformation and loading (ETL) tool. There is also an online analytical processing engine (OLAP), client analysis tools, and other applications to manage the processing of collected data.
One of the main features of a Data Warehouse is that the information is classified by subject (customers, products, etc.). In fact, what really defines a Data Warehouse is the type of data it contains and the people who use it.