Broadly, any metalanguage is language or symbols used when language itself is being discussed or examined. In logic and linguistics, a metalanguage is a language used to make statements about statements in another language (the object language). Expressions in a metalanguage are often distinguished from those in an object language by the use of italics, quotation marks, or writing on a separate line.
There is a variety of recognized metalanguages, including embedded, ordered, and nested (or, hierarchical).
An embedded metalanguage is a language formally, naturally and firmly fixed in an object language. This idea is found in Douglas Hofstadter's book, Gödel, Escher, Bach, in a discussion of the relationship between formal languages and number theory: “... it is in the nature of any formalization of number theory that its metalanguage is embedded within it.”.
It occurs in natural, or informal, languages, as well—such as in English, where descriptors, i.e. adjectives, adverbs, and possessive pronouns, constitute an embedded metalanguage; and where nouns, verbs, and, in some instances, adjectives and adverbs, constitute an object language. Thus, the adjective “red” in the phrase “red