The concept of Langue (language) and Parole (speech) was given by the Swiss linguist Ferdinand de Saussure. These terms appeared first in the book “A Course In General Linguistics” (Cours de linguistique générale) – a series of class notes that were compiled and published by Saussure’s students in 1916 after his death.
Saussure, a linguist from the Structuralist school of linguistics, believed Language to be a system of signs. Each sign conventionally signifies something. Also, the relationship between a sign and what it signifies is arbitrary. It is important to note here that Saussure defined language in purely structural terms.
Langue, then, for Saussure, is nothing but all the abstract rules and conventions of this system of signs (or language). These rules, as we know, do not occur in the world explicitly (as linguists, we only try to study and describe these rules).
It is interesting to know that every language user has an instinctive, innate understanding of these rules that make up language. Note that this statement was not actually given by Saussure. Structuralism in language did not describe language as an instinct (Pinker, 1995) or as a mentalist, cognitive object (Chomsky). These assumptions were postulated in later studies.
Nest, Saussure said that language users make use of Langue to produce “actual utterances”. These actual utterances (Parole), in this way, make concrete use of the abstract rules of languages.
For example, language users can have the concept of past tense in their language. They would know in an abstract fashion that auxiliary verbs get inflected for past tense in their language. Hence, English language users would use the auxiliary verb “was” for describing things of past. Similarly an abstract understanding of the rules for plurality would tell him to use “was” in singular contexts and the auxiliary verb “were” in case the context is plural. Similarly, they would have understanding of the rule that says addition of the suffix –ing to a verb is for progressive aspect or continuing action. This abstract understanding of the rules for marking a verb with aspect, making an auxiliary into past tense, singular or plural agreement, etc. is only a very small part of Langue. Langue is a system of so many rules and conventions. When language users actually make utterances about past events, each such utterance constitutes Parole. Hence, the utterance “They were sleeping” would be a part of Parole.
When a child acquires languages, he actually makes generalizations and forms hypothesis about these rules from the linguistic environment. As linguists, we try to explicitly state these rules, but these rules do not actually occur in nature as such.