What is ETL?
What does ETL stand for and why does every Data Engineer learn it?
Extract, Transform, Load. Extract pulls data from a source, Transform cleans it, Load writes it to its destination. Almost every data pipeline ever built follows this pattern, even if the modern variant ELT swaps the order.
ETL stands for Extract, Transform, Load. Extract reads data from a source (API, database, file). Transform cleans and reshapes it (drop nulls, rename columns, join with reference data). Load writes the final result to a destination (data warehouse, dashboard, file).
This three-step pattern is so foundational that the word "ETL" is often synonymous with "data pipeline." Modern variants exist — ELT loads raw data first and transforms inside the warehouse — but the underlying flow is the same. Understanding ETL is non-negotiable for any DE role.