Ferdinand de Saussure was a Swiss linguist born on November 26, 1857, known as a foundational figure in modern linguistics. His key contributions include the concepts of the linguistic sign, the distinction between langue (language) and parole (speech), and the synchronic and diachronic methods of language study, which shaped the future of linguistic theory and various fields like semiotics. Saussure's theories emphasize the arbitrary nature of signs and their role as a structured system, profoundly influencing contemporary understanding of language.