Ferdinand de Saussure originated and defined the concepts of langue and parole in his seminal work Course in General Linguistics. These became the bedrock of twentieth century linguistics and influenced sociology and anthropology. They also led to Saussure's development of semiology, called semiotics in the U.S.
The dominating study of linguistics, the study of language in all its parts, had been the study of the change in language over time. This field of linguistic study is termed diachronic linguistics. Saussure, in relation to langue and parole, drew a distinction between diachronic linguistic study and synchronic linguistic study, which, in contrast to diachronic, is the study of language as it is used by any given speaker or group of speakers in any given moment in time: it is the study of language in a static, non-historical context.
Langue is the linguistic code, that which comprises the linguistic structure of a language, whereas parole is the use of the code (use of langue) for particular purposes with particular meaning in particular circumstances. Saussure posited langue, the code of language, as the proper domain of linguistic study. By doing so, he separated code (structure, langue) from meaning (parole).
This distinction between langue and parole--code and meaning--is made more complex by Saussure's position, as stated in semiology, that synchronic sign systems of signifier (symbol denoting meaning) and signified (the thing denoted by a sign/signifier) both comprise meaning and are comprised of meaning. Saussure asserts this dialectical (augmenting) relationship of signifier/signified is evident even while he separates langue (code/structure) and parole (realization of meaning in a synchronic context).