Ferdinand de Saussure introduced the concepts of Langue and Parole to distinguish between different aspects of language:
Langue: This refers to the underlying system or structure of a language, including its grammar, rules, and conventions. It is not the same as any individual act of speaking or writing (parole). Langue can be thought of as the abstract, systematic aspect of language.
Parole: This refers to the actual instances of language use, such as individual speech acts or instances of writing. Parole is the concrete manifestation of langue in use.