It is a process of extracting the data and transforming into required business format via loading into DWH.
ETL is often a complex combination of process and technology that consumes a significant portion of the data warehouse development efforts and requires the skills of business analysts, database designers, and application developers. It is not a one time event as new data is added to the Data Warehouse periodically – monthly, daily, hourly. Because ETL is an integral, on-going, and recurring part of a data warehouse
It is not the strongest of the species that survives, nor the most intelligent that survives.But it is the one that is the most adaptable to change.
Above quote also applies to businesses. Adaptive businesses sustain.
In order to observe the changing trend or in other words predict the market trend, business intelligence plays a pivotal role.