ETL (extract, transform and load) extracts data from multiple sources, transforms the data from one format to another, and then loads it into the target database or data warehouse. ELT (extract, load and transform), on the other hand, extracts data from a source, loads it into a target database, and transforms data within that database. However, for ELT to work, source and destination systems should both be databases. The major difference between these two processing techniques is where the transformation takes place. In ELT, the integration server handles the load of transformation, whereas in ELT, the transformation takes place in the source or destination database.