ETL / ELT
Problem
Sales says:
country = "AT"
CRM says:
country = "Austria"
Another system stores:
country_id = 17
Analytics needs one coherent representation.
Solution — ETL / ELT
Extract data, transform it into useful forms and load it into analytical storage—or load first and transform there.
Core idea: ETL/ELT turns heterogeneous source data into usable analytical data.