What's the difference between DAX and Power Query (or M)?

Question

I have been working on Power BI for a while now and I often get confused when I browse through help topics of it. They often refer to the functions and formulas being used as DA

Answer 1

One other thing worth mentioning re performance optimisation is that you should "prune" your datatset (remove rows / remove columns) as far "upstream" - of the data processing sequence - as possible; this means such operations are better done in Power Query than DAX; some further advice from MS here: https://docs.microsoft.com/en-us/power-bi/power-bi-reports-performance