Direct answer: Power Query is the data-preparation layer of Power BI. You connect to a source, apply recorded transformation steps, and load clean tables to the model. It is the same editor as in Excel.
Typical flow
- Get Data and choose the source.
- Promote headers, set data types.
- Remove or rename columns, trim and clean text.
- Merge or append tables.
- Close & Apply.
Do work upstream
Splitting columns and filtering rows in Power Query is usually better than creating DAX calculated columns, because it keeps the model lean.
Reference and staging queries
Keep a raw query (disable load) and build cleaned queries from it. Name steps clearly.
Common mistakes
- Changing types late, causing errors
- Merging before removing duplicate keys
- Loading unused tables
Conclusion
Clean data first, then model. Learn the full chain in the Power BI course.