What does "data extraction" mean in the ETL process?

Data extraction in the ETL (Extract, Transform, Load) process refers specifically to the retrieval of data from various sources. This step is crucial as it involves gathering raw data from different databases, data warehouses, APIs, or any other data source before processing it. The goal of extraction is to ensure that relevant data is collected and made available for further manipulation and analysis.

Once the data is extracted, it can then be transformed, which involves cleaning, structuring, and preparing the data for analysis, and finally loaded into a destination system such as a data warehouse or database. In the context of ETL, extraction lays the foundation for the subsequent processes that enhance the data's quality and usability.