Introduction to M
If you want to unlock the full potential of Power Query, you have to learn M. M is the unofficial name for Power Query’s formula language, and Power Query generates M code for each step in your query. The Power Query user interface also allows you to write your own M expressions in situations where you need more flexibility and control over what your query does.
The biggest problem with the M language, from an Excel developer’s point of view, is that it bears little resemblance to Excel formulas or VBA: it is a functional language like F#. You will have to learn new syntax, new functions, and new ways of doing familiar ...