This document discusses ETL (Extract, Transform, Load) processes in data warehousing. It defines ETL as extracting data from source systems, transforming it (e.g. performing calculations and conforming data), and loading it into a data warehouse or target storage. The document notes that 70-80% of BI/DW projects rely on reliable ETL processes and that the ETL market is large and growing. It provides examples of how to implement ETL using scripting, ETL tools, or custom coding and outlines key features of ETL tools.