In response to the question I made a new colleague in BI. What is ETL? To obtain the data warehouse sequentially develop the data extraction, processing, and finally loading into the reservoir. The extraction process involves obtaining information from different sources (databases and operational files), both internally and externally, through data management tools. We must transform the data into those required for deposit. The process consists of filtering, cleaning, cleansing, standardization and integration of information. This should be done, since the operational databases are designed to support multiple production applications often differ in format, then, may be the same data elements, but names and inconsistent formats and encodings. All these inconsistencies should be resolved before taking the last step of this process that corresponds to the loading of data into the data warehouse. Reference Book: The Data Warehouse ETL Toolkit: Practical Techniques for Extracting, ...