Overview:

ETL (Extract/Transform/Load) is a process which extracts data from source systems and transforms the information into a consistent data type, then loads the data into a single depository. ETL testing refers to the process of validating, verifying, and qualifying data while preventing duplicate records as well as data loss.

ETL testing ensures that the transfer of data from heterogeneous sources to the central data warehouse. It differs from data reconciliation used in testing in that ETL testing is applied to data warehouse systems and used to obtain relevant information for analytics and business intelligence.