ETL involves the following steps: (a) Extract data from homogeneous or heterogeneous data sources which are often managed by different people. An intrinsic part of the extraction involves data validation to confirm whether the data pulled from the sources have the correct/expected values; (b) Transform the data for storing it in proper format or structure for querying and analysis purposes; An important function of transformation is the cleaning of data; and, (c) Load the data into the final target (database, operational data store, data mart, or data warehouse). ETL processes can involve considerable complexity, and significant operational problems can occur. SYNONYM. ETLn/ahttps://en.wikipedia.org/wiki/Extract%2C_transform%2C_load