This project delves into the ETL (Extract, Transform, Load) process, a critical component of data warehousing. It begins with an introduction to ETL, highlighting its importance in integrating data from various sources into data marts and data warehouses, enabling business intelligence and advanced data insights. The project outlines the three core steps of ETL: extraction, transformation, and loading, detailing how data is identified, retrieved, structured, and loaded into the data warehouse. It categorizes ETL technologies into sophisticated, enabler, simpler, and rudimentary types, discussing their advantages and disadvantages. The project presents an example of ETL technologies, including Informatica, Data Junction, Transact SQL, Java, and COBOL, as well as modern tools like Apache NiFi, Jasper, and Pentaho Data Integration. It emphasizes the significance of defining business requirements before selecting an ETL tool and outlines the key considerations of cost control, revenue generation, security, compliance, and new initiatives in ETL technologies. Furthermore, the project details the ETL plan, encompassing extraction, cleaning, transformation, and loading steps. It specifies target data requirements, including dimension and fact tables, and lists data sources and mappings. Data extraction rules, transformation, and cleansing rules are thoroughly explained, providing a comprehensive understanding of the ETL process.