Defining features of the data warehouse are: separate, subject-oriented, integrated, time-variant, and nonvolatile.
You may use a top-down approach and build a large, comprehensive, enterprise data warehouse; or, you may use a bottom-up approach and build small, independent, departmental data marts. In spite of some advantages, both approaches have serious shortcomings.
A viable practical approach is to build conformed data marts, which together form the corporate data warehouse.
Data warehouse building blocks or components are: source data, data staging, data storage, information delivery, metadata, and management and control.
In a data warehouse, metadata is especially significant because it acts as the glue holding all the components together and serves as a roadmap for the end-users.