Data warehousing conceptsData: Data is collection of raw material in unorganized format, which refers an object.Information: Organized data that has been meaning & value.Knowledge: Processed data or information that conveys understanding or learning applicable to a problem or activity.In Data warehouse, the data is converted into information format to get knowledge for making decisions. What is Data Warehouse?Data warehouse is arelational databasemanagement which is used forreportingandanalyzing the data to take managerial decisions. It is a central repository of data which is created by integrating data from different sources and converting that data into information format for taking managerial decisions. Data warehouses store current data as well as historical data and Read only data for management reporting such as annual and quarterly comparisons. Eg: Big Bazar-->C.E.O needs data annual data --> Ipod --> Hyd --> 2011 -->SalesIn an organization we have different departments like Sales dept, product dept, HR dept etc.. Now C.E.O wants ipod sales in hyd location for the year 2011. So, C.E.O collects the data from sales dept and product dept and need to take some decisions on profits & loss based on the information. If he want to take decisions he need historical data also.