What is a staging area? Do we need it? What is the purpose of a staging area?

A staging area is storage area between the operational data source systems and the data presentation system. Staging area is a common place to keep extracted data from different source systems before applying business rules (transformation, cleansing). Staging area is place where you hold temporary tables on data warehouse server. Staging tables are connected to work area or fact tables. Staging area plays an important role in performing data validation, transformations, cleansing and merging before loading the data into warehouse. In the absence of the Staging area, there is a load on the source system or the data presentation system to have the data conformed to the dimension model. This is the primary reason for the existence of a staging area in any ETL system. In addition it also offers a platform for carrying out data cleansing.