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Find the M code that Power Query has been generating behind the UI all along. Learn to open the Advanced Editor, read a generated query, and make your first hand edit.

A translation guide: the ten most common Power Query UI operations — filter rows, add column, merge queries, group by — and the exact M code each one generates.

Now that you've seen M code in the wild, understand what kind of language it is. M is functional, immutable, and lazy — three properties that explain most of its surprising behaviors.

The let/in block is M's fundamental building block. Every query you write is a let expression. Learn how named steps compose into a pipeline and why step order isn't execution order.

M has three container types: records (rows), lists (columns), and tables (grids). Understanding how they relate to each other is the key to reading and writing most M code.

each is shorthand for a single-argument function. It appears in every Table.AddColumn, Table.SelectRows, and List.Transform call. Understanding it unlocks the whole standard library.

M is strongly typed. Learn the primitive types, how nullable types work, and why type annotations on Table.AddColumn matter for performance.

Null propagates silently through M expressions. Learn how null flows through comparisons, arithmetic, and function calls — and how to defend against it with the ?? operator.

if/then/else, logical operators, and how conditional logic works in a language where everything is an expression. The building block for conditional columns and branching transformations.

Errors in M are values, not exceptions. Learn try/otherwise, how to catch errors cell-by-cell in a table, and when to let errors propagate versus recover from them.