Refers to the process by which data is: – Extracted from sources – Transformed or standardized for storing in the proper heterogeneous format – and Loaded into the final store or warehouse. The ETL process is commonly run in parallel with transformation processes executing as data is being extracted from sources. ETL systems commonly integrate data from multiple applications (systems) managed and operated by different employees. For example, a cost accounting system may combine data from payroll, sales, and purchasing.