**Extract-Transform-Load** (ETL) is a process of loading large amounts of from a source system to a destination system, typically a data warehouse. 

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# Phases of the ETL process:

1. **Extraction:** Acquiring data from the source systems
2. **Transformation:** Conforming data to a standardized dimensional schema.
3. **Loading:** Loading data into data mart for consumption
4. **Post-processing:** Loading data into a cube for browsing






# ETL testing

ETL testing is a *data-centric* process to validate that the data has been transformed and loaded from the source to the destination. It is most commonly used in Data warehousing. 

There are several tests and checks involved in the process. These usually include:

What is Extract-Transform-Load (ETL) testing?

ETL testing validates data transformation and loading between source and destination systems, crucial for data warehousing.