This text provides an in-depth look at the Power Query M formula language, used for data transformation in various Microsoft services like Power BI and Excel. It covers fundamental concepts such as expressions, values (including primitive, list, record, and binary types), and the let expression for defining steps in a query. The documentation details the lexical and syntactic grammar of the language, explaining how identifiers, keywords, literals, operators, and comments are structured and used. It also explores functions, parameters, environment evaluation, type system (including primitive and custom types), and a wide array of standard library functions for data manipulation, including operations on text, lists, records, and tables, alongside functions for interacting with external data sources.