ETL (Extract, Transform, Load) is a data integration process where data is extracted from different source systems, transformed to meet the operational needs (such as data cleansing, normalization, and aggregation), and then loaded into a target database or data warehouse. This method is widely used in traditional data warehousing and business intelligence applications, enabling organizations to consolidate data from various sources into a single repository for reporting and analysis. ETL processes are typically automated and scheduled to run at specific intervals.