The process of designing, building, and maintaining is a data warehouse system. A new advance in data-base management is whereby copies of all the data bases in a company are maintained in one location and can be assessed by employees at any locale. 

A data warehouse is a central repository for all or significant parts of the data that an enterprise's various business systems collect. The term was coined by W. H. Inmon. IBM sometimes uses the term "information warehouse."  

Typically, a data warehouse is housed on an enterprise mainframe server. Data from various online transaction processing (OLTP) applications and other sources is selectively extracted and organized on the data warehouse database for use by analytical applications and user queries. Data warehousing emphasizes the capture of data from diverse sources for useful analysis and access, but does not generally start from the point-of-view of the end user or knowledge worker who may need access to specialized, sometimes local databases. The latter idea is known as the data mart 

The data warehousing market consists of tools, technologies, and methodologies that allow for the construction, usage, management, and maintenance of the hardware and software used for a data warehouse, as well as the actual data itself. Surveys indicate Data Warehousing will be the single largest IT initiative after completion of Y2K efforts.  

Data warehousing is currently a $38 Billion market and we estimate 40% growth per annum through at 2009. 

The term Data Warehouse was coined by Bill Inmon in 1990, which he defined in the following way: "A warehouse is a subject-oriented, integrated, time-variant and non-volatile collection of data in support of management's decision making process" 

It is Subject Oriented, Data that gives information about a particular subject instead of about a company's ongoing operations and Integrated, Data that is gathered into the data warehouse from a variety of sources and merged into a coherent whole. It is Time-variant: All data in the data warehouse is identified with a particular time period.

Non-volatile,Data is stable in a data warehouse. More data is added but data is never removed. This enables management to gain a consistent picture of the business.