Extract, Transform, and Load (ETL) processes are essential components of a data warehousing system. These processes are responsible for extracting data from various sources, transforming it into a suitable format, and loading it into the data warehouse. Let's explore each step in detail:

1. Extract: During the extraction phase, data is gathered from different source systems such as databases, flat files, APIs, or web scraping. This step involves identifying the relevant data needed for analysis and pulling it from the sources.

2. Transform: Once the data is extracted, it often requires cleaning and manipulation to ensure consistency and compatibility with the data warehouse schema. Transformations may include removing duplicates, handling missing values, normalizing data, or applying business rules and calculations.

3. Load: After the data has been extracted and transformed, it is ready to be loaded into the data warehouse. This step involves mapping the transformed data to the target data warehouse schema and inserting it into the respective tables.

ETL processes play a crucial role in ensuring that the data within the data warehouse is accurate, reliable, and consistent. These processes enable data integration from multiple sources, thereby providing a unified view for analytical purposes.