Extract
the process of extracting,reading or getting data from a variety of data source like database, file, stream or even programmatically generated memory data.
the process of converting the extracted data from its previous form into the one it needs to be in so that it can be transferred or stored into other data store. Generally, transformation are done by using defined rules. These rules can be for simply migrating data from one source to another or for building up a whole new data by combining multiple data sources with complex converting business logic.