Structuralism
Early in the 20th century, Saussure introduced the idea of language as a static system of interconnected units, defined through the oppositions between them. By introducing a distinction between diachronic to synchronic analyses of language, he laid the foundation of the modern discipline of linguistics. Saussure also introduced several basic dimensions of linguistic analysis that are still foundational in many contemporary linguistic theories, such as the distinctions between syntagm and paradigm, and the langue- parole distinction, distinguishing language as an abstract system (langue) from language as a concrete manifestation of this system (parole). Substantial additional contributions following Saussure's definition of a structural approach to language came from The Prague school, Leonard Bloomfield, Charles F. Hockett, Louis Hjelmslev, Émile Benveniste and Roman Jakobson.
Read more about this topic: Linguistics, Schools of Thought