A data warehouse is nothing new; in fact, data warehousing was being practiced for years even before the term was coined by Bill Inmon in his seminal work Building the Data Warehouse. Although Inmon is often referred to as the "father of data warehousing," this is not entirely the case. To give credit where credit's due, it was the Irish IBM architects Barry Devlin and Paul Murphy who, in 1988, laid the foundations for what we today call a data warehouse. It's interesting to see that the concept of the Business Data Warehouse (BDW) Devlin and Murphy described in their original article hasn't changed that much over the past decades. They define the BDW as "the single logical storehouse of all the information used to report on the business," which is still exactly what it is.
Feel free to just skim over this chapter or even skip it if you're already familiar with the basics of data warehousing.
To get a better understanding of the nature of a data warehouse we will add Inmon's original description as well. He defined a data warehouse as being:
Subject oriented—All entities and events relating to a specific subject (e.g., "sales") are linked together.
Time variant—All changes to the data are tracked to enable reporting that shows changes over time.
Non-volatile—When data is entered into the data warehouse, it is never overwritten or deleted.
Integrated—The data warehouse contains data from multiple source systems after being cleaned and conformed. ...